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Case Study – Methods, Examples and Guide

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A case study is a research method that involves an in-depth examination and analysis of a particular phenomenon or case, such as an individual, organization, community, event, or situation.

It is a qualitative research approach that aims to provide a detailed and comprehensive understanding of the case being studied. Case studies typically involve multiple sources of data, including interviews, observations, documents, and artifacts, which are analyzed using various techniques, such as content analysis, thematic analysis, and grounded theory. The findings of a case study are often used to develop theories, inform policy or practice, or generate new research questions.

Types of Case Study

Types and Methods of Case Study are as follows:

Single-Case Study

A single-case study is an in-depth analysis of a single case. This type of case study is useful when the researcher wants to understand a specific phenomenon in detail.

For Example , A researcher might conduct a single-case study on a particular individual to understand their experiences with a particular health condition or a specific organization to explore their management practices. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of a single-case study are often used to generate new research questions, develop theories, or inform policy or practice.

Multiple-Case Study

A multiple-case study involves the analysis of several cases that are similar in nature. This type of case study is useful when the researcher wants to identify similarities and differences between the cases.

For Example, a researcher might conduct a multiple-case study on several companies to explore the factors that contribute to their success or failure. The researcher collects data from each case, compares and contrasts the findings, and uses various techniques to analyze the data, such as comparative analysis or pattern-matching. The findings of a multiple-case study can be used to develop theories, inform policy or practice, or generate new research questions.

Exploratory Case Study

An exploratory case study is used to explore a new or understudied phenomenon. This type of case study is useful when the researcher wants to generate hypotheses or theories about the phenomenon.

For Example, a researcher might conduct an exploratory case study on a new technology to understand its potential impact on society. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as grounded theory or content analysis. The findings of an exploratory case study can be used to generate new research questions, develop theories, or inform policy or practice.

Descriptive Case Study

A descriptive case study is used to describe a particular phenomenon in detail. This type of case study is useful when the researcher wants to provide a comprehensive account of the phenomenon.

For Example, a researcher might conduct a descriptive case study on a particular community to understand its social and economic characteristics. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of a descriptive case study can be used to inform policy or practice or generate new research questions.

Instrumental Case Study

An instrumental case study is used to understand a particular phenomenon that is instrumental in achieving a particular goal. This type of case study is useful when the researcher wants to understand the role of the phenomenon in achieving the goal.

For Example, a researcher might conduct an instrumental case study on a particular policy to understand its impact on achieving a particular goal, such as reducing poverty. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of an instrumental case study can be used to inform policy or practice or generate new research questions.

Case Study Data Collection Methods

Here are some common data collection methods for case studies:

Interviews involve asking questions to individuals who have knowledge or experience relevant to the case study. Interviews can be structured (where the same questions are asked to all participants) or unstructured (where the interviewer follows up on the responses with further questions). Interviews can be conducted in person, over the phone, or through video conferencing.

Observations

Observations involve watching and recording the behavior and activities of individuals or groups relevant to the case study. Observations can be participant (where the researcher actively participates in the activities) or non-participant (where the researcher observes from a distance). Observations can be recorded using notes, audio or video recordings, or photographs.

Documents can be used as a source of information for case studies. Documents can include reports, memos, emails, letters, and other written materials related to the case study. Documents can be collected from the case study participants or from public sources.

Surveys involve asking a set of questions to a sample of individuals relevant to the case study. Surveys can be administered in person, over the phone, through mail or email, or online. Surveys can be used to gather information on attitudes, opinions, or behaviors related to the case study.

Artifacts are physical objects relevant to the case study. Artifacts can include tools, equipment, products, or other objects that provide insights into the case study phenomenon.

How to conduct Case Study Research

Conducting a case study research involves several steps that need to be followed to ensure the quality and rigor of the study. Here are the steps to conduct case study research:

• Define the research questions: The first step in conducting a case study research is to define the research questions. The research questions should be specific, measurable, and relevant to the case study phenomenon under investigation.
• Select the case: The next step is to select the case or cases to be studied. The case should be relevant to the research questions and should provide rich and diverse data that can be used to answer the research questions.
• Collect data: Data can be collected using various methods, such as interviews, observations, documents, surveys, and artifacts. The data collection method should be selected based on the research questions and the nature of the case study phenomenon.
• Analyze the data: The data collected from the case study should be analyzed using various techniques, such as content analysis, thematic analysis, or grounded theory. The analysis should be guided by the research questions and should aim to provide insights and conclusions relevant to the research questions.
• Draw conclusions: The conclusions drawn from the case study should be based on the data analysis and should be relevant to the research questions. The conclusions should be supported by evidence and should be clearly stated.
• Validate the findings: The findings of the case study should be validated by reviewing the data and the analysis with participants or other experts in the field. This helps to ensure the validity and reliability of the findings.
• Write the report: The final step is to write the report of the case study research. The report should provide a clear description of the case study phenomenon, the research questions, the data collection methods, the data analysis, the findings, and the conclusions. The report should be written in a clear and concise manner and should follow the guidelines for academic writing.

Examples of Case Study

Here are some examples of case study research:

• The Hawthorne Studies : Conducted between 1924 and 1932, the Hawthorne Studies were a series of case studies conducted by Elton Mayo and his colleagues to examine the impact of work environment on employee productivity. The studies were conducted at the Hawthorne Works plant of the Western Electric Company in Chicago and included interviews, observations, and experiments.
• The Stanford Prison Experiment: Conducted in 1971, the Stanford Prison Experiment was a case study conducted by Philip Zimbardo to examine the psychological effects of power and authority. The study involved simulating a prison environment and assigning participants to the role of guards or prisoners. The study was controversial due to the ethical issues it raised.
• The Challenger Disaster: The Challenger Disaster was a case study conducted to examine the causes of the Space Shuttle Challenger explosion in 1986. The study included interviews, observations, and analysis of data to identify the technical, organizational, and cultural factors that contributed to the disaster.
• The Enron Scandal: The Enron Scandal was a case study conducted to examine the causes of the Enron Corporation’s bankruptcy in 2001. The study included interviews, analysis of financial data, and review of documents to identify the accounting practices, corporate culture, and ethical issues that led to the company’s downfall.
• The Fukushima Nuclear Disaster : The Fukushima Nuclear Disaster was a case study conducted to examine the causes of the nuclear accident that occurred at the Fukushima Daiichi Nuclear Power Plant in Japan in 2011. The study included interviews, analysis of data, and review of documents to identify the technical, organizational, and cultural factors that contributed to the disaster.

Application of Case Study

Case studies have a wide range of applications across various fields and industries. Here are some examples:

Business and Management

Case studies are widely used in business and management to examine real-life situations and develop problem-solving skills. Case studies can help students and professionals to develop a deep understanding of business concepts, theories, and best practices.

Case studies are used in healthcare to examine patient care, treatment options, and outcomes. Case studies can help healthcare professionals to develop critical thinking skills, diagnose complex medical conditions, and develop effective treatment plans.

Case studies are used in education to examine teaching and learning practices. Case studies can help educators to develop effective teaching strategies, evaluate student progress, and identify areas for improvement.

Social Sciences

Case studies are widely used in social sciences to examine human behavior, social phenomena, and cultural practices. Case studies can help researchers to develop theories, test hypotheses, and gain insights into complex social issues.

Law and Ethics

Case studies are used in law and ethics to examine legal and ethical dilemmas. Case studies can help lawyers, policymakers, and ethical professionals to develop critical thinking skills, analyze complex cases, and make informed decisions.

Purpose of Case Study

The purpose of a case study is to provide a detailed analysis of a specific phenomenon, issue, or problem in its real-life context. A case study is a qualitative research method that involves the in-depth exploration and analysis of a particular case, which can be an individual, group, organization, event, or community.

The primary purpose of a case study is to generate a comprehensive and nuanced understanding of the case, including its history, context, and dynamics. Case studies can help researchers to identify and examine the underlying factors, processes, and mechanisms that contribute to the case and its outcomes. This can help to develop a more accurate and detailed understanding of the case, which can inform future research, practice, or policy.

Case studies can also serve other purposes, including:

• Illustrating a theory or concept: Case studies can be used to illustrate and explain theoretical concepts and frameworks, providing concrete examples of how they can be applied in real-life situations.
• Developing hypotheses: Case studies can help to generate hypotheses about the causal relationships between different factors and outcomes, which can be tested through further research.
• Providing insight into complex issues: Case studies can provide insights into complex and multifaceted issues, which may be difficult to understand through other research methods.
• Informing practice or policy: Case studies can be used to inform practice or policy by identifying best practices, lessons learned, or areas for improvement.

Advantages of Case Study Research

There are several advantages of case study research, including:

• In-depth exploration: Case study research allows for a detailed exploration and analysis of a specific phenomenon, issue, or problem in its real-life context. This can provide a comprehensive understanding of the case and its dynamics, which may not be possible through other research methods.
• Rich data: Case study research can generate rich and detailed data, including qualitative data such as interviews, observations, and documents. This can provide a nuanced understanding of the case and its complexity.
• Holistic perspective: Case study research allows for a holistic perspective of the case, taking into account the various factors, processes, and mechanisms that contribute to the case and its outcomes. This can help to develop a more accurate and comprehensive understanding of the case.
• Theory development: Case study research can help to develop and refine theories and concepts by providing empirical evidence and concrete examples of how they can be applied in real-life situations.
• Practical application: Case study research can inform practice or policy by identifying best practices, lessons learned, or areas for improvement.
• Contextualization: Case study research takes into account the specific context in which the case is situated, which can help to understand how the case is influenced by the social, cultural, and historical factors of its environment.

Limitations of Case Study Research

There are several limitations of case study research, including:

• Limited generalizability : Case studies are typically focused on a single case or a small number of cases, which limits the generalizability of the findings. The unique characteristics of the case may not be applicable to other contexts or populations, which may limit the external validity of the research.
• Biased sampling: Case studies may rely on purposive or convenience sampling, which can introduce bias into the sample selection process. This may limit the representativeness of the sample and the generalizability of the findings.
• Subjectivity: Case studies rely on the interpretation of the researcher, which can introduce subjectivity into the analysis. The researcher’s own biases, assumptions, and perspectives may influence the findings, which may limit the objectivity of the research.
• Limited control: Case studies are typically conducted in naturalistic settings, which limits the control that the researcher has over the environment and the variables being studied. This may limit the ability to establish causal relationships between variables.
• Time-consuming: Case studies can be time-consuming to conduct, as they typically involve a detailed exploration and analysis of a specific case. This may limit the feasibility of conducting multiple case studies or conducting case studies in a timely manner.
• Resource-intensive: Case studies may require significant resources, including time, funding, and expertise. This may limit the ability of researchers to conduct case studies in resource-constrained settings.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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Methodology

• What Is a Case Study? | Definition, Examples & Methods

What Is a Case Study? | Definition, Examples & Methods

Published on May 8, 2019 by Shona McCombes . Revised on November 20, 2023.

A case study is a detailed study of a specific subject, such as a person, group, place, event, organization, or phenomenon. Case studies are commonly used in social, educational, clinical, and business research.

A case study research design usually involves qualitative methods , but quantitative methods are sometimes also used. Case studies are good for describing , comparing, evaluating and understanding different aspects of a research problem .

Table of contents

When to do a case study, step 1: select a case, step 2: build a theoretical framework, step 3: collect your data, step 4: describe and analyze the case, other interesting articles.

A case study is an appropriate research design when you want to gain concrete, contextual, in-depth knowledge about a specific real-world subject. It allows you to explore the key characteristics, meanings, and implications of the case.

Case studies are often a good choice in a thesis or dissertation . They keep your project focused and manageable when you don’t have the time or resources to do large-scale research.

You might use just one complex case study where you explore a single subject in depth, or conduct multiple case studies to compare and illuminate different aspects of your research problem.

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Once you have developed your problem statement and research questions , you should be ready to choose the specific case that you want to focus on. A good case study should have the potential to:

• Provide new or unexpected insights into the subject
• Challenge or complicate existing assumptions and theories
• Propose practical courses of action to resolve a problem
• Open up new directions for future research

TipIf your research is more practical in nature and aims to simultaneously investigate an issue as you solve it, consider conducting action research instead.

Unlike quantitative or experimental research , a strong case study does not require a random or representative sample. In fact, case studies often deliberately focus on unusual, neglected, or outlying cases which may shed new light on the research problem.

Example of an outlying case studyIn the 1960s the town of Roseto, Pennsylvania was discovered to have extremely low rates of heart disease compared to the US average. It became an important case study for understanding previously neglected causes of heart disease.

However, you can also choose a more common or representative case to exemplify a particular category, experience or phenomenon.

Example of a representative case studyIn the 1920s, two sociologists used Muncie, Indiana as a case study of a typical American city that supposedly exemplified the changing culture of the US at the time.

While case studies focus more on concrete details than general theories, they should usually have some connection with theory in the field. This way the case study is not just an isolated description, but is integrated into existing knowledge about the topic. It might aim to:

• Exemplify a theory by showing how it explains the case under investigation
• Expand on a theory by uncovering new concepts and ideas that need to be incorporated
• Challenge a theory by exploring an outlier case that doesn’t fit with established assumptions

To ensure that your analysis of the case has a solid academic grounding, you should conduct a literature review of sources related to the topic and develop a theoretical framework . This means identifying key concepts and theories to guide your analysis and interpretation.

There are many different research methods you can use to collect data on your subject. Case studies tend to focus on qualitative data using methods such as interviews , observations , and analysis of primary and secondary sources (e.g., newspaper articles, photographs, official records). Sometimes a case study will also collect quantitative data.

Example of a mixed methods case studyFor a case study of a wind farm development in a rural area, you could collect quantitative data on employment rates and business revenue, collect qualitative data on local people’s perceptions and experiences, and analyze local and national media coverage of the development.

The aim is to gain as thorough an understanding as possible of the case and its context.

In writing up the case study, you need to bring together all the relevant aspects to give as complete a picture as possible of the subject.

How you report your findings depends on the type of research you are doing. Some case studies are structured like a standard scientific paper or thesis , with separate sections or chapters for the methods , results and discussion .

Others are written in a more narrative style, aiming to explore the case from various angles and analyze its meanings and implications (for example, by using textual analysis or discourse analysis ).

In all cases, though, make sure to give contextual details about the case, connect it back to the literature and theory, and discuss how it fits into wider patterns or debates.

If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.

• Normal distribution
• Degrees of freedom
• Null hypothesis
• Discourse analysis
• Control groups
• Mixed methods research
• Non-probability sampling
• Quantitative research
• Ecological validity

Research bias

• Rosenthal effect
• Implicit bias
• Cognitive bias
• Selection bias
• Negativity bias
• Status quo bias

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• Published: 27 June 2011

The case study approach

• Sarah Crowe 1 ,
• Kathrin Cresswell 2 ,
• Ann Robertson 2 ,
• Guro Huby 3 ,
• Anthony Avery 1 &
• Aziz Sheikh 2  

BMC Medical Research Methodology volume  11 , Article number:  100 ( 2011 ) Cite this article

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The case study approach allows in-depth, multi-faceted explorations of complex issues in their real-life settings. The value of the case study approach is well recognised in the fields of business, law and policy, but somewhat less so in health services research. Based on our experiences of conducting several health-related case studies, we reflect on the different types of case study design, the specific research questions this approach can help answer, the data sources that tend to be used, and the particular advantages and disadvantages of employing this methodological approach. The paper concludes with key pointers to aid those designing and appraising proposals for conducting case study research, and a checklist to help readers assess the quality of case study reports.

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Introduction

The case study approach is particularly useful to employ when there is a need to obtain an in-depth appreciation of an issue, event or phenomenon of interest, in its natural real-life context. Our aim in writing this piece is to provide insights into when to consider employing this approach and an overview of key methodological considerations in relation to the design, planning, analysis, interpretation and reporting of case studies.

The illustrative 'grand round', 'case report' and 'case series' have a long tradition in clinical practice and research. Presenting detailed critiques, typically of one or more patients, aims to provide insights into aspects of the clinical case and, in doing so, illustrate broader lessons that may be learnt. In research, the conceptually-related case study approach can be used, for example, to describe in detail a patient's episode of care, explore professional attitudes to and experiences of a new policy initiative or service development or more generally to 'investigate contemporary phenomena within its real-life context' [ 1 ]. Based on our experiences of conducting a range of case studies, we reflect on when to consider using this approach, discuss the key steps involved and illustrate, with examples, some of the practical challenges of attaining an in-depth understanding of a 'case' as an integrated whole. In keeping with previously published work, we acknowledge the importance of theory to underpin the design, selection, conduct and interpretation of case studies[ 2 ]. In so doing, we make passing reference to the different epistemological approaches used in case study research by key theoreticians and methodologists in this field of enquiry.

This paper is structured around the following main questions: What is a case study? What are case studies used for? How are case studies conducted? What are the potential pitfalls and how can these be avoided? We draw in particular on four of our own recently published examples of case studies (see Tables 1 , 2 , 3 and 4 ) and those of others to illustrate our discussion[ 3 – 7 ].

What is a case study?

A case study is a research approach that is used to generate an in-depth, multi-faceted understanding of a complex issue in its real-life context. It is an established research design that is used extensively in a wide variety of disciplines, particularly in the social sciences. A case study can be defined in a variety of ways (Table 5 ), the central tenet being the need to explore an event or phenomenon in depth and in its natural context. It is for this reason sometimes referred to as a "naturalistic" design; this is in contrast to an "experimental" design (such as a randomised controlled trial) in which the investigator seeks to exert control over and manipulate the variable(s) of interest.

Stake's work has been particularly influential in defining the case study approach to scientific enquiry. He has helpfully characterised three main types of case study: intrinsic , instrumental and collective [ 8 ]. An intrinsic case study is typically undertaken to learn about a unique phenomenon. The researcher should define the uniqueness of the phenomenon, which distinguishes it from all others. In contrast, the instrumental case study uses a particular case (some of which may be better than others) to gain a broader appreciation of an issue or phenomenon. The collective case study involves studying multiple cases simultaneously or sequentially in an attempt to generate a still broader appreciation of a particular issue.

These are however not necessarily mutually exclusive categories. In the first of our examples (Table 1 ), we undertook an intrinsic case study to investigate the issue of recruitment of minority ethnic people into the specific context of asthma research studies, but it developed into a instrumental case study through seeking to understand the issue of recruitment of these marginalised populations more generally, generating a number of the findings that are potentially transferable to other disease contexts[ 3 ]. In contrast, the other three examples (see Tables 2 , 3 and 4 ) employed collective case study designs to study the introduction of workforce reconfiguration in primary care, the implementation of electronic health records into hospitals, and to understand the ways in which healthcare students learn about patient safety considerations[ 4 – 6 ]. Although our study focusing on the introduction of General Practitioners with Specialist Interests (Table 2 ) was explicitly collective in design (four contrasting primary care organisations were studied), is was also instrumental in that this particular professional group was studied as an exemplar of the more general phenomenon of workforce redesign[ 4 ].

What are case studies used for?

According to Yin, case studies can be used to explain, describe or explore events or phenomena in the everyday contexts in which they occur[ 1 ]. These can, for example, help to understand and explain causal links and pathways resulting from a new policy initiative or service development (see Tables 2 and 3 , for example)[ 1 ]. In contrast to experimental designs, which seek to test a specific hypothesis through deliberately manipulating the environment (like, for example, in a randomised controlled trial giving a new drug to randomly selected individuals and then comparing outcomes with controls),[ 9 ] the case study approach lends itself well to capturing information on more explanatory ' how ', 'what' and ' why ' questions, such as ' how is the intervention being implemented and received on the ground?'. The case study approach can offer additional insights into what gaps exist in its delivery or why one implementation strategy might be chosen over another. This in turn can help develop or refine theory, as shown in our study of the teaching of patient safety in undergraduate curricula (Table 4 )[ 6 , 10 ]. Key questions to consider when selecting the most appropriate study design are whether it is desirable or indeed possible to undertake a formal experimental investigation in which individuals and/or organisations are allocated to an intervention or control arm? Or whether the wish is to obtain a more naturalistic understanding of an issue? The former is ideally studied using a controlled experimental design, whereas the latter is more appropriately studied using a case study design.

Case studies may be approached in different ways depending on the epistemological standpoint of the researcher, that is, whether they take a critical (questioning one's own and others' assumptions), interpretivist (trying to understand individual and shared social meanings) or positivist approach (orientating towards the criteria of natural sciences, such as focusing on generalisability considerations) (Table 6 ). Whilst such a schema can be conceptually helpful, it may be appropriate to draw on more than one approach in any case study, particularly in the context of conducting health services research. Doolin has, for example, noted that in the context of undertaking interpretative case studies, researchers can usefully draw on a critical, reflective perspective which seeks to take into account the wider social and political environment that has shaped the case[ 11 ].

How are case studies conducted?

Here, we focus on the main stages of research activity when planning and undertaking a case study; the crucial stages are: defining the case; selecting the case(s); collecting and analysing the data; interpreting data; and reporting the findings.

Defining the case

Carefully formulated research question(s), informed by the existing literature and a prior appreciation of the theoretical issues and setting(s), are all important in appropriately and succinctly defining the case[ 8 , 12 ]. Crucially, each case should have a pre-defined boundary which clarifies the nature and time period covered by the case study (i.e. its scope, beginning and end), the relevant social group, organisation or geographical area of interest to the investigator, the types of evidence to be collected, and the priorities for data collection and analysis (see Table 7 )[ 1 ]. A theory driven approach to defining the case may help generate knowledge that is potentially transferable to a range of clinical contexts and behaviours; using theory is also likely to result in a more informed appreciation of, for example, how and why interventions have succeeded or failed[ 13 ].

For example, in our evaluation of the introduction of electronic health records in English hospitals (Table 3 ), we defined our cases as the NHS Trusts that were receiving the new technology[ 5 ]. Our focus was on how the technology was being implemented. However, if the primary research interest had been on the social and organisational dimensions of implementation, we might have defined our case differently as a grouping of healthcare professionals (e.g. doctors and/or nurses). The precise beginning and end of the case may however prove difficult to define. Pursuing this same example, when does the process of implementation and adoption of an electronic health record system really begin or end? Such judgements will inevitably be influenced by a range of factors, including the research question, theory of interest, the scope and richness of the gathered data and the resources available to the research team.

Selecting the case(s)

The decision on how to select the case(s) to study is a very important one that merits some reflection. In an intrinsic case study, the case is selected on its own merits[ 8 ]. The case is selected not because it is representative of other cases, but because of its uniqueness, which is of genuine interest to the researchers. This was, for example, the case in our study of the recruitment of minority ethnic participants into asthma research (Table 1 ) as our earlier work had demonstrated the marginalisation of minority ethnic people with asthma, despite evidence of disproportionate asthma morbidity[ 14 , 15 ]. In another example of an intrinsic case study, Hellstrom et al.[ 16 ] studied an elderly married couple living with dementia to explore how dementia had impacted on their understanding of home, their everyday life and their relationships.

For an instrumental case study, selecting a "typical" case can work well[ 8 ]. In contrast to the intrinsic case study, the particular case which is chosen is of less importance than selecting a case that allows the researcher to investigate an issue or phenomenon. For example, in order to gain an understanding of doctors' responses to health policy initiatives, Som undertook an instrumental case study interviewing clinicians who had a range of responsibilities for clinical governance in one NHS acute hospital trust[ 17 ]. Sampling a "deviant" or "atypical" case may however prove even more informative, potentially enabling the researcher to identify causal processes, generate hypotheses and develop theory.

In collective or multiple case studies, a number of cases are carefully selected. This offers the advantage of allowing comparisons to be made across several cases and/or replication. Choosing a "typical" case may enable the findings to be generalised to theory (i.e. analytical generalisation) or to test theory by replicating the findings in a second or even a third case (i.e. replication logic)[ 1 ]. Yin suggests two or three literal replications (i.e. predicting similar results) if the theory is straightforward and five or more if the theory is more subtle. However, critics might argue that selecting 'cases' in this way is insufficiently reflexive and ill-suited to the complexities of contemporary healthcare organisations.

The selected case study site(s) should allow the research team access to the group of individuals, the organisation, the processes or whatever else constitutes the chosen unit of analysis for the study. Access is therefore a central consideration; the researcher needs to come to know the case study site(s) well and to work cooperatively with them. Selected cases need to be not only interesting but also hospitable to the inquiry [ 8 ] if they are to be informative and answer the research question(s). Case study sites may also be pre-selected for the researcher, with decisions being influenced by key stakeholders. For example, our selection of case study sites in the evaluation of the implementation and adoption of electronic health record systems (see Table 3 ) was heavily influenced by NHS Connecting for Health, the government agency that was responsible for overseeing the National Programme for Information Technology (NPfIT)[ 5 ]. This prominent stakeholder had already selected the NHS sites (through a competitive bidding process) to be early adopters of the electronic health record systems and had negotiated contracts that detailed the deployment timelines.

It is also important to consider in advance the likely burden and risks associated with participation for those who (or the site(s) which) comprise the case study. Of particular importance is the obligation for the researcher to think through the ethical implications of the study (e.g. the risk of inadvertently breaching anonymity or confidentiality) and to ensure that potential participants/participating sites are provided with sufficient information to make an informed choice about joining the study. The outcome of providing this information might be that the emotive burden associated with participation, or the organisational disruption associated with supporting the fieldwork, is considered so high that the individuals or sites decide against participation.

In our example of evaluating implementations of electronic health record systems, given the restricted number of early adopter sites available to us, we sought purposively to select a diverse range of implementation cases among those that were available[ 5 ]. We chose a mixture of teaching, non-teaching and Foundation Trust hospitals, and examples of each of the three electronic health record systems procured centrally by the NPfIT. At one recruited site, it quickly became apparent that access was problematic because of competing demands on that organisation. Recognising the importance of full access and co-operative working for generating rich data, the research team decided not to pursue work at that site and instead to focus on other recruited sites.

Collecting the data

In order to develop a thorough understanding of the case, the case study approach usually involves the collection of multiple sources of evidence, using a range of quantitative (e.g. questionnaires, audits and analysis of routinely collected healthcare data) and more commonly qualitative techniques (e.g. interviews, focus groups and observations). The use of multiple sources of data (data triangulation) has been advocated as a way of increasing the internal validity of a study (i.e. the extent to which the method is appropriate to answer the research question)[ 8 , 18 – 21 ]. An underlying assumption is that data collected in different ways should lead to similar conclusions, and approaching the same issue from different angles can help develop a holistic picture of the phenomenon (Table 2 )[ 4 ].

Brazier and colleagues used a mixed-methods case study approach to investigate the impact of a cancer care programme[ 22 ]. Here, quantitative measures were collected with questionnaires before, and five months after, the start of the intervention which did not yield any statistically significant results. Qualitative interviews with patients however helped provide an insight into potentially beneficial process-related aspects of the programme, such as greater, perceived patient involvement in care. The authors reported how this case study approach provided a number of contextual factors likely to influence the effectiveness of the intervention and which were not likely to have been obtained from quantitative methods alone.

In collective or multiple case studies, data collection needs to be flexible enough to allow a detailed description of each individual case to be developed (e.g. the nature of different cancer care programmes), before considering the emerging similarities and differences in cross-case comparisons (e.g. to explore why one programme is more effective than another). It is important that data sources from different cases are, where possible, broadly comparable for this purpose even though they may vary in nature and depth.

Analysing, interpreting and reporting case studies

Making sense and offering a coherent interpretation of the typically disparate sources of data (whether qualitative alone or together with quantitative) is far from straightforward. Repeated reviewing and sorting of the voluminous and detail-rich data are integral to the process of analysis. In collective case studies, it is helpful to analyse data relating to the individual component cases first, before making comparisons across cases. Attention needs to be paid to variations within each case and, where relevant, the relationship between different causes, effects and outcomes[ 23 ]. Data will need to be organised and coded to allow the key issues, both derived from the literature and emerging from the dataset, to be easily retrieved at a later stage. An initial coding frame can help capture these issues and can be applied systematically to the whole dataset with the aid of a qualitative data analysis software package.

The Framework approach is a practical approach, comprising of five stages (familiarisation; identifying a thematic framework; indexing; charting; mapping and interpretation) , to managing and analysing large datasets particularly if time is limited, as was the case in our study of recruitment of South Asians into asthma research (Table 1 )[ 3 , 24 ]. Theoretical frameworks may also play an important role in integrating different sources of data and examining emerging themes. For example, we drew on a socio-technical framework to help explain the connections between different elements - technology; people; and the organisational settings within which they worked - in our study of the introduction of electronic health record systems (Table 3 )[ 5 ]. Our study of patient safety in undergraduate curricula drew on an evaluation-based approach to design and analysis, which emphasised the importance of the academic, organisational and practice contexts through which students learn (Table 4 )[ 6 ].

Case study findings can have implications both for theory development and theory testing. They may establish, strengthen or weaken historical explanations of a case and, in certain circumstances, allow theoretical (as opposed to statistical) generalisation beyond the particular cases studied[ 12 ]. These theoretical lenses should not, however, constitute a strait-jacket and the cases should not be "forced to fit" the particular theoretical framework that is being employed.

When reporting findings, it is important to provide the reader with enough contextual information to understand the processes that were followed and how the conclusions were reached. In a collective case study, researchers may choose to present the findings from individual cases separately before amalgamating across cases. Care must be taken to ensure the anonymity of both case sites and individual participants (if agreed in advance) by allocating appropriate codes or withholding descriptors. In the example given in Table 3 , we decided against providing detailed information on the NHS sites and individual participants in order to avoid the risk of inadvertent disclosure of identities[ 5 , 25 ].

What are the potential pitfalls and how can these be avoided?

The case study approach is, as with all research, not without its limitations. When investigating the formal and informal ways undergraduate students learn about patient safety (Table 4 ), for example, we rapidly accumulated a large quantity of data. The volume of data, together with the time restrictions in place, impacted on the depth of analysis that was possible within the available resources. This highlights a more general point of the importance of avoiding the temptation to collect as much data as possible; adequate time also needs to be set aside for data analysis and interpretation of what are often highly complex datasets.

Case study research has sometimes been criticised for lacking scientific rigour and providing little basis for generalisation (i.e. producing findings that may be transferable to other settings)[ 1 ]. There are several ways to address these concerns, including: the use of theoretical sampling (i.e. drawing on a particular conceptual framework); respondent validation (i.e. participants checking emerging findings and the researcher's interpretation, and providing an opinion as to whether they feel these are accurate); and transparency throughout the research process (see Table 8 )[ 8 , 18 – 21 , 23 , 26 ]. Transparency can be achieved by describing in detail the steps involved in case selection, data collection, the reasons for the particular methods chosen, and the researcher's background and level of involvement (i.e. being explicit about how the researcher has influenced data collection and interpretation). Seeking potential, alternative explanations, and being explicit about how interpretations and conclusions were reached, help readers to judge the trustworthiness of the case study report. Stake provides a critique checklist for a case study report (Table 9 )[ 8 ].

Conclusions

The case study approach allows, amongst other things, critical events, interventions, policy developments and programme-based service reforms to be studied in detail in a real-life context. It should therefore be considered when an experimental design is either inappropriate to answer the research questions posed or impossible to undertake. Considering the frequency with which implementations of innovations are now taking place in healthcare settings and how well the case study approach lends itself to in-depth, complex health service research, we believe this approach should be more widely considered by researchers. Though inherently challenging, the research case study can, if carefully conceptualised and thoughtfully undertaken and reported, yield powerful insights into many important aspects of health and healthcare delivery.

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Acknowledgements

We are grateful to the participants and colleagues who contributed to the individual case studies that we have drawn on. This work received no direct funding, but it has been informed by projects funded by Asthma UK, the NHS Service Delivery Organisation, NHS Connecting for Health Evaluation Programme, and Patient Safety Research Portfolio. We would also like to thank the expert reviewers for their insightful and constructive feedback. Our thanks are also due to Dr. Allison Worth who commented on an earlier draft of this manuscript.

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Case Study | Definition, Examples & Methods

Published on 5 May 2022 by Shona McCombes . Revised on 30 January 2023.

A case study is a detailed study of a specific subject, such as a person, group, place, event, organisation, or phenomenon. Case studies are commonly used in social, educational, clinical, and business research.

A case study research design usually involves qualitative methods , but quantitative methods are sometimes also used. Case studies are good for describing , comparing, evaluating, and understanding different aspects of a research problem .

Table of contents

When to do a case study, step 1: select a case, step 2: build a theoretical framework, step 3: collect your data, step 4: describe and analyse the case.

A case study is an appropriate research design when you want to gain concrete, contextual, in-depth knowledge about a specific real-world subject. It allows you to explore the key characteristics, meanings, and implications of the case.

Case studies are often a good choice in a thesis or dissertation . They keep your project focused and manageable when you don’t have the time or resources to do large-scale research.

You might use just one complex case study where you explore a single subject in depth, or conduct multiple case studies to compare and illuminate different aspects of your research problem.

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Once you have developed your problem statement and research questions , you should be ready to choose the specific case that you want to focus on. A good case study should have the potential to:

• Provide new or unexpected insights into the subject
• Challenge or complicate existing assumptions and theories
• Propose practical courses of action to resolve a problem
• Open up new directions for future research

Unlike quantitative or experimental research, a strong case study does not require a random or representative sample. In fact, case studies often deliberately focus on unusual, neglected, or outlying cases which may shed new light on the research problem.

If you find yourself aiming to simultaneously investigate and solve an issue, consider conducting action research . As its name suggests, action research conducts research and takes action at the same time, and is highly iterative and flexible. 

However, you can also choose a more common or representative case to exemplify a particular category, experience, or phenomenon.

While case studies focus more on concrete details than general theories, they should usually have some connection with theory in the field. This way the case study is not just an isolated description, but is integrated into existing knowledge about the topic. It might aim to:

• Exemplify a theory by showing how it explains the case under investigation
• Expand on a theory by uncovering new concepts and ideas that need to be incorporated
• Challenge a theory by exploring an outlier case that doesn’t fit with established assumptions

To ensure that your analysis of the case has a solid academic grounding, you should conduct a literature review of sources related to the topic and develop a theoretical framework . This means identifying key concepts and theories to guide your analysis and interpretation.

There are many different research methods you can use to collect data on your subject. Case studies tend to focus on qualitative data using methods such as interviews, observations, and analysis of primary and secondary sources (e.g., newspaper articles, photographs, official records). Sometimes a case study will also collect quantitative data .

The aim is to gain as thorough an understanding as possible of the case and its context.

In writing up the case study, you need to bring together all the relevant aspects to give as complete a picture as possible of the subject.

How you report your findings depends on the type of research you are doing. Some case studies are structured like a standard scientific paper or thesis, with separate sections or chapters for the methods , results , and discussion .

Others are written in a more narrative style, aiming to explore the case from various angles and analyse its meanings and implications (for example, by using textual analysis or discourse analysis ).

In all cases, though, make sure to give contextual details about the case, connect it back to the literature and theory, and discuss how it fits into wider patterns or debates.

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The Ultimate Guide to Qualitative Research - Part 1: The Basics

• Introduction and overview
• What is qualitative research?
• What is qualitative data?
• Examples of qualitative data
• Qualitative vs. quantitative research
• Mixed methods
• Qualitative research preparation
• Theoretical perspective
• Theoretical framework
• Literature reviews

Research question

• Conceptual framework
• Conceptual vs. theoretical framework

Data collection

• Qualitative research methods
• Focus groups
• Observational research

What is a case study?

Applications for case study research, what is a good case study, process of case study design, benefits and limitations of case studies.

• Ethnographical research
• Ethical considerations
• Confidentiality and privacy
• Power dynamics
• Reflexivity

Case studies

Case studies are essential to qualitative research , offering a lens through which researchers can investigate complex phenomena within their real-life contexts. This chapter explores the concept, purpose, applications, examples, and types of case studies and provides guidance on how to conduct case study research effectively.

Whereas quantitative methods look at phenomena at scale, case study research looks at a concept or phenomenon in considerable detail. While analyzing a single case can help understand one perspective regarding the object of research inquiry, analyzing multiple cases can help obtain a more holistic sense of the topic or issue. Let's provide a basic definition of a case study, then explore its characteristics and role in the qualitative research process.

Definition of a case study

A case study in qualitative research is a strategy of inquiry that involves an in-depth investigation of a phenomenon within its real-world context. It provides researchers with the opportunity to acquire an in-depth understanding of intricate details that might not be as apparent or accessible through other methods of research. The specific case or cases being studied can be a single person, group, or organization – demarcating what constitutes a relevant case worth studying depends on the researcher and their research question .

Among qualitative research methods , a case study relies on multiple sources of evidence, such as documents, artifacts, interviews , or observations , to present a complete and nuanced understanding of the phenomenon under investigation. The objective is to illuminate the readers' understanding of the phenomenon beyond its abstract statistical or theoretical explanations.

Characteristics of case studies

Case studies typically possess a number of distinct characteristics that set them apart from other research methods. These characteristics include a focus on holistic description and explanation, flexibility in the design and data collection methods, reliance on multiple sources of evidence, and emphasis on the context in which the phenomenon occurs.

Furthermore, case studies can often involve a longitudinal examination of the case, meaning they study the case over a period of time. These characteristics allow case studies to yield comprehensive, in-depth, and richly contextualized insights about the phenomenon of interest.

The role of case studies in research

Case studies hold a unique position in the broader landscape of research methods aimed at theory development. They are instrumental when the primary research interest is to gain an intensive, detailed understanding of a phenomenon in its real-life context.

In addition, case studies can serve different purposes within research - they can be used for exploratory, descriptive, or explanatory purposes, depending on the research question and objectives. This flexibility and depth make case studies a valuable tool in the toolkit of qualitative researchers.

Remember, a well-conducted case study can offer a rich, insightful contribution to both academic and practical knowledge through theory development or theory verification, thus enhancing our understanding of complex phenomena in their real-world contexts.

What is the purpose of a case study?

Case study research aims for a more comprehensive understanding of phenomena, requiring various research methods to gather information for qualitative analysis . Ultimately, a case study can allow the researcher to gain insight into a particular object of inquiry and develop a theoretical framework relevant to the research inquiry.

Why use case studies in qualitative research?

Using case studies as a research strategy depends mainly on the nature of the research question and the researcher's access to the data.

Conducting case study research provides a level of detail and contextual richness that other research methods might not offer. They are beneficial when there's a need to understand complex social phenomena within their natural contexts.

The explanatory, exploratory, and descriptive roles of case studies

Case studies can take on various roles depending on the research objectives. They can be exploratory when the research aims to discover new phenomena or define new research questions; they are descriptive when the objective is to depict a phenomenon within its context in a detailed manner; and they can be explanatory if the goal is to understand specific relationships within the studied context. Thus, the versatility of case studies allows researchers to approach their topic from different angles, offering multiple ways to uncover and interpret the data .

The impact of case studies on knowledge development

Case studies play a significant role in knowledge development across various disciplines. Analysis of cases provides an avenue for researchers to explore phenomena within their context based on the collected data.

This can result in the production of rich, practical insights that can be instrumental in both theory-building and practice. Case studies allow researchers to delve into the intricacies and complexities of real-life situations, uncovering insights that might otherwise remain hidden.

Types of case studies

In qualitative research , a case study is not a one-size-fits-all approach. Depending on the nature of the research question and the specific objectives of the study, researchers might choose to use different types of case studies. These types differ in their focus, methodology, and the level of detail they provide about the phenomenon under investigation.

Understanding these types is crucial for selecting the most appropriate approach for your research project and effectively achieving your research goals. Let's briefly look at the main types of case studies.

Exploratory case studies

Exploratory case studies are typically conducted to develop a theory or framework around an understudied phenomenon. They can also serve as a precursor to a larger-scale research project. Exploratory case studies are useful when a researcher wants to identify the key issues or questions which can spur more extensive study or be used to develop propositions for further research. These case studies are characterized by flexibility, allowing researchers to explore various aspects of a phenomenon as they emerge, which can also form the foundation for subsequent studies.

Descriptive case studies

Descriptive case studies aim to provide a complete and accurate representation of a phenomenon or event within its context. These case studies are often based on an established theoretical framework, which guides how data is collected and analyzed. The researcher is concerned with describing the phenomenon in detail, as it occurs naturally, without trying to influence or manipulate it.

Explanatory case studies

Explanatory case studies are focused on explanation - they seek to clarify how or why certain phenomena occur. Often used in complex, real-life situations, they can be particularly valuable in clarifying causal relationships among concepts and understanding the interplay between different factors within a specific context.

Intrinsic, instrumental, and collective case studies

These three categories of case studies focus on the nature and purpose of the study. An intrinsic case study is conducted when a researcher has an inherent interest in the case itself. Instrumental case studies are employed when the case is used to provide insight into a particular issue or phenomenon. A collective case study, on the other hand, involves studying multiple cases simultaneously to investigate some general phenomena.

Each type of case study serves a different purpose and has its own strengths and challenges. The selection of the type should be guided by the research question and objectives, as well as the context and constraints of the research.

The flexibility, depth, and contextual richness offered by case studies make this approach an excellent research method for various fields of study. They enable researchers to investigate real-world phenomena within their specific contexts, capturing nuances that other research methods might miss. Across numerous fields, case studies provide valuable insights into complex issues.

Critical information systems research

Case studies provide a detailed understanding of the role and impact of information systems in different contexts. They offer a platform to explore how information systems are designed, implemented, and used and how they interact with various social, economic, and political factors. Case studies in this field often focus on examining the intricate relationship between technology, organizational processes, and user behavior, helping to uncover insights that can inform better system design and implementation.

Health research

Health research is another field where case studies are highly valuable. They offer a way to explore patient experiences, healthcare delivery processes, and the impact of various interventions in a real-world context.

Case studies can provide a deep understanding of a patient's journey, giving insights into the intricacies of disease progression, treatment effects, and the psychosocial aspects of health and illness.

Asthma research studies

Specifically within medical research, studies on asthma often employ case studies to explore the individual and environmental factors that influence asthma development, management, and outcomes. A case study can provide rich, detailed data about individual patients' experiences, from the triggers and symptoms they experience to the effectiveness of various management strategies. This can be crucial for developing patient-centered asthma care approaches.

Other fields

Apart from the fields mentioned, case studies are also extensively used in business and management research, education research, and political sciences, among many others. They provide an opportunity to delve into the intricacies of real-world situations, allowing for a comprehensive understanding of various phenomena.

Case studies, with their depth and contextual focus, offer unique insights across these varied fields. They allow researchers to illuminate the complexities of real-life situations, contributing to both theory and practice.

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Understanding the key elements of case study design is crucial for conducting rigorous and impactful case study research. A well-structured design guides the researcher through the process, ensuring that the study is methodologically sound and its findings are reliable and valid. The main elements of case study design include the research question , propositions, units of analysis, and the logic linking the data to the propositions.

The research question is the foundation of any research study. A good research question guides the direction of the study and informs the selection of the case, the methods of collecting data, and the analysis techniques. A well-formulated research question in case study research is typically clear, focused, and complex enough to merit further detailed examination of the relevant case(s).

Propositions

Propositions, though not necessary in every case study, provide a direction by stating what we might expect to find in the data collected. They guide how data is collected and analyzed by helping researchers focus on specific aspects of the case. They are particularly important in explanatory case studies, which seek to understand the relationships among concepts within the studied phenomenon.

Units of analysis

The unit of analysis refers to the case, or the main entity or entities that are being analyzed in the study. In case study research, the unit of analysis can be an individual, a group, an organization, a decision, an event, or even a time period. It's crucial to clearly define the unit of analysis, as it shapes the qualitative data analysis process by allowing the researcher to analyze a particular case and synthesize analysis across multiple case studies to draw conclusions.

Argumentation

This refers to the inferential model that allows researchers to draw conclusions from the data. The researcher needs to ensure that there is a clear link between the data, the propositions (if any), and the conclusions drawn. This argumentation is what enables the researcher to make valid and credible inferences about the phenomenon under study.

Understanding and carefully considering these elements in the design phase of a case study can significantly enhance the quality of the research. It can help ensure that the study is methodologically sound and its findings contribute meaningful insights about the case.

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Conducting a case study involves several steps, from defining the research question and selecting the case to collecting and analyzing data . This section outlines these key stages, providing a practical guide on how to conduct case study research.

Defining the research question

The first step in case study research is defining a clear, focused research question. This question should guide the entire research process, from case selection to analysis. It's crucial to ensure that the research question is suitable for a case study approach. Typically, such questions are exploratory or descriptive in nature and focus on understanding a phenomenon within its real-life context.

Selecting and defining the case

The selection of the case should be based on the research question and the objectives of the study. It involves choosing a unique example or a set of examples that provide rich, in-depth data about the phenomenon under investigation. After selecting the case, it's crucial to define it clearly, setting the boundaries of the case, including the time period and the specific context.

Previous research can help guide the case study design. When considering a case study, an example of a case could be taken from previous case study research and used to define cases in a new research inquiry. Considering recently published examples can help understand how to select and define cases effectively.

Developing a detailed case study protocol

A case study protocol outlines the procedures and general rules to be followed during the case study. This includes the data collection methods to be used, the sources of data, and the procedures for analysis. Having a detailed case study protocol ensures consistency and reliability in the study.

The protocol should also consider how to work with the people involved in the research context to grant the research team access to collecting data. As mentioned in previous sections of this guide, establishing rapport is an essential component of qualitative research as it shapes the overall potential for collecting and analyzing data.

Collecting data

Gathering data in case study research often involves multiple sources of evidence, including documents, archival records, interviews, observations, and physical artifacts. This allows for a comprehensive understanding of the case. The process for gathering data should be systematic and carefully documented to ensure the reliability and validity of the study.

Analyzing and interpreting data

The next step is analyzing the data. This involves organizing the data , categorizing it into themes or patterns , and interpreting these patterns to answer the research question. The analysis might also involve comparing the findings with prior research or theoretical propositions.

Writing the case study report

The final step is writing the case study report . This should provide a detailed description of the case, the data, the analysis process, and the findings. The report should be clear, organized, and carefully written to ensure that the reader can understand the case and the conclusions drawn from it.

Each of these steps is crucial in ensuring that the case study research is rigorous, reliable, and provides valuable insights about the case.

The type, depth, and quality of data in your study can significantly influence the validity and utility of the study. In case study research, data is usually collected from multiple sources to provide a comprehensive and nuanced understanding of the case. This section will outline the various methods of collecting data used in case study research and discuss considerations for ensuring the quality of the data.

Interviews are a common method of gathering data in case study research. They can provide rich, in-depth data about the perspectives, experiences, and interpretations of the individuals involved in the case. Interviews can be structured , semi-structured , or unstructured , depending on the research question and the degree of flexibility needed.

Observations

Observations involve the researcher observing the case in its natural setting, providing first-hand information about the case and its context. Observations can provide data that might not be revealed in interviews or documents, such as non-verbal cues or contextual information.

Documents and artifacts

Documents and archival records provide a valuable source of data in case study research. They can include reports, letters, memos, meeting minutes, email correspondence, and various public and private documents related to the case.

These records can provide historical context, corroborate evidence from other sources, and offer insights into the case that might not be apparent from interviews or observations.

Physical artifacts refer to any physical evidence related to the case, such as tools, products, or physical environments. These artifacts can provide tangible insights into the case, complementing the data gathered from other sources.

Ensuring the quality of data collection

Determining the quality of data in case study research requires careful planning and execution. It's crucial to ensure that the data is reliable, accurate, and relevant to the research question. This involves selecting appropriate methods of collecting data, properly training interviewers or observers, and systematically recording and storing the data. It also includes considering ethical issues related to collecting and handling data, such as obtaining informed consent and ensuring the privacy and confidentiality of the participants.

Data analysis

Analyzing case study research involves making sense of the rich, detailed data to answer the research question. This process can be challenging due to the volume and complexity of case study data. However, a systematic and rigorous approach to analysis can ensure that the findings are credible and meaningful. This section outlines the main steps and considerations in analyzing data in case study research.

Organizing the data

The first step in the analysis is organizing the data. This involves sorting the data into manageable sections, often according to the data source or the theme. This step can also involve transcribing interviews, digitizing physical artifacts, or organizing observational data.

Categorizing and coding the data

Once the data is organized, the next step is to categorize or code the data. This involves identifying common themes, patterns, or concepts in the data and assigning codes to relevant data segments. Coding can be done manually or with the help of software tools, and in either case, qualitative analysis software can greatly facilitate the entire coding process. Coding helps to reduce the data to a set of themes or categories that can be more easily analyzed.

Identifying patterns and themes

After coding the data, the researcher looks for patterns or themes in the coded data. This involves comparing and contrasting the codes and looking for relationships or patterns among them. The identified patterns and themes should help answer the research question.

Interpreting the data

Once patterns and themes have been identified, the next step is to interpret these findings. This involves explaining what the patterns or themes mean in the context of the research question and the case. This interpretation should be grounded in the data, but it can also involve drawing on theoretical concepts or prior research.

Verification of the data

The last step in the analysis is verification. This involves checking the accuracy and consistency of the analysis process and confirming that the findings are supported by the data. This can involve re-checking the original data, checking the consistency of codes, or seeking feedback from research participants or peers.

Like any research method , case study research has its strengths and limitations. Researchers must be aware of these, as they can influence the design, conduct, and interpretation of the study.

Understanding the strengths and limitations of case study research can also guide researchers in deciding whether this approach is suitable for their research question . This section outlines some of the key strengths and limitations of case study research.

Benefits include the following:

• Rich, detailed data: One of the main strengths of case study research is that it can generate rich, detailed data about the case. This can provide a deep understanding of the case and its context, which can be valuable in exploring complex phenomena.
• Flexibility: Case study research is flexible in terms of design , data collection , and analysis . A sufficient degree of flexibility allows the researcher to adapt the study according to the case and the emerging findings.
• Real-world context: Case study research involves studying the case in its real-world context, which can provide valuable insights into the interplay between the case and its context.
• Multiple sources of evidence: Case study research often involves collecting data from multiple sources , which can enhance the robustness and validity of the findings.

On the other hand, researchers should consider the following limitations:

• Generalizability: A common criticism of case study research is that its findings might not be generalizable to other cases due to the specificity and uniqueness of each case.
• Time and resource intensive: Case study research can be time and resource intensive due to the depth of the investigation and the amount of collected data.
• Complexity of analysis: The rich, detailed data generated in case study research can make analyzing the data challenging.
• Subjectivity: Given the nature of case study research, there may be a higher degree of subjectivity in interpreting the data , so researchers need to reflect on this and transparently convey to audiences how the research was conducted.

Being aware of these strengths and limitations can help researchers design and conduct case study research effectively and interpret and report the findings appropriately.

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What the Case Study Method Really Teaches

• Nitin Nohria

Seven meta-skills that stick even if the cases fade from memory.

It’s been 100 years since Harvard Business School began using the case study method. Beyond teaching specific subject matter, the case study method excels in instilling meta-skills in students. This article explains the importance of seven such skills: preparation, discernment, bias recognition, judgement, collaboration, curiosity, and self-confidence.

During my decade as dean of Harvard Business School, I spent hundreds of hours talking with our alumni. To enliven these conversations, I relied on a favorite question: “What was the most important thing you learned from your time in our MBA program?”

• Nitin Nohria is the George F. Baker Jr. and Distinguished Service University Professor. He served as the 10th dean of Harvard Business School, from 2010 to 2020.

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Case Study Research Method in Psychology

Saul McLeod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Learn about our Editorial Process

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

Case studies are in-depth investigations of a person, group, event, or community. Typically, data is gathered from various sources using several methods (e.g., observations & interviews).

The case study research method originated in clinical medicine (the case history, i.e., the patient’s personal history). In psychology, case studies are often confined to the study of a particular individual.

The information is mainly biographical and relates to events in the individual’s past (i.e., retrospective), as well as to significant events that are currently occurring in his or her everyday life.

The case study is not a research method, but researchers select methods of data collection and analysis that will generate material suitable for case studies.

Freud (1909a, 1909b) conducted very detailed investigations into the private lives of his patients in an attempt to both understand and help them overcome their illnesses.

This makes it clear that the case study is a method that should only be used by a psychologist, therapist, or psychiatrist, i.e., someone with a professional qualification.

There is an ethical issue of competence. Only someone qualified to diagnose and treat a person can conduct a formal case study relating to atypical (i.e., abnormal) behavior or atypical development.

 Famous Case Studies

• Anna O – One of the most famous case studies, documenting psychoanalyst Josef Breuer’s treatment of “Anna O” (real name Bertha Pappenheim) for hysteria in the late 1800s using early psychoanalytic theory.
• Little Hans – A child psychoanalysis case study published by Sigmund Freud in 1909 analyzing his five-year-old patient Herbert Graf’s house phobia as related to the Oedipus complex.
• Bruce/Brenda – Gender identity case of the boy (Bruce) whose botched circumcision led psychologist John Money to advise gender reassignment and raise him as a girl (Brenda) in the 1960s.
• Genie Wiley – Linguistics/psychological development case of the victim of extreme isolation abuse who was studied in 1970s California for effects of early language deprivation on acquiring speech later in life.
• Phineas Gage – One of the most famous neuropsychology case studies analyzes personality changes in railroad worker Phineas Gage after an 1848 brain injury involving a tamping iron piercing his skull.

Clinical Case Studies

• Studying the effectiveness of psychotherapy approaches with an individual patient
• Assessing and treating mental illnesses like depression, anxiety disorders, PTSD
• Neuropsychological cases investigating brain injuries or disorders

Child Psychology Case Studies

• Studying psychological development from birth through adolescence
• Cases of learning disabilities, autism spectrum disorders, ADHD
• Effects of trauma, abuse, deprivation on development

Types of Case Studies

• Explanatory case studies : Used to explore causation in order to find underlying principles. Helpful for doing qualitative analysis to explain presumed causal links.
• Exploratory case studies : Used to explore situations where an intervention being evaluated has no clear set of outcomes. It helps define questions and hypotheses for future research.
• Descriptive case studies : Describe an intervention or phenomenon and the real-life context in which it occurred. It is helpful for illustrating certain topics within an evaluation.
• Multiple-case studies : Used to explore differences between cases and replicate findings across cases. Helpful for comparing and contrasting specific cases.
• Intrinsic : Used to gain a better understanding of a particular case. Helpful for capturing the complexity of a single case.
• Collective : Used to explore a general phenomenon using multiple case studies. Helpful for jointly studying a group of cases in order to inquire into the phenomenon.

Where Do You Find Data for a Case Study?

There are several places to find data for a case study. The key is to gather data from multiple sources to get a complete picture of the case and corroborate facts or findings through triangulation of evidence. Most of this information is likely qualitative (i.e., verbal description rather than measurement), but the psychologist might also collect numerical data.

1. Primary sources

• Interviews – Interviewing key people related to the case to get their perspectives and insights. The interview is an extremely effective procedure for obtaining information about an individual, and it may be used to collect comments from the person’s friends, parents, employer, workmates, and others who have a good knowledge of the person, as well as to obtain facts from the person him or herself.
• Observations – Observing behaviors, interactions, processes, etc., related to the case as they unfold in real-time.
• Documents & Records – Reviewing private documents, diaries, public records, correspondence, meeting minutes, etc., relevant to the case.

2. Secondary sources

• News/Media – News coverage of events related to the case study.
• Academic articles – Journal articles, dissertations etc. that discuss the case.
• Government reports – Official data and records related to the case context.
• Books/films – Books, documentaries or films discussing the case.

3. Archival records

Searching historical archives, museum collections and databases to find relevant documents, visual/audio records related to the case history and context.

Public archives like newspapers, organizational records, photographic collections could all include potentially relevant pieces of information to shed light on attitudes, cultural perspectives, common practices and historical contexts related to psychology.

4. Organizational records

Organizational records offer the advantage of often having large datasets collected over time that can reveal or confirm psychological insights.

Of course, privacy and ethical concerns regarding confidential data must be navigated carefully.

However, with proper protocols, organizational records can provide invaluable context and empirical depth to qualitative case studies exploring the intersection of psychology and organizations.

• Organizational/industrial psychology research : Organizational records like employee surveys, turnover/retention data, policies, incident reports etc. may provide insight into topics like job satisfaction, workplace culture and dynamics, leadership issues, employee behaviors etc.
• Clinical psychology : Therapists/hospitals may grant access to anonymized medical records to study aspects like assessments, diagnoses, treatment plans etc. This could shed light on clinical practices.
• School psychology : Studies could utilize anonymized student records like test scores, grades, disciplinary issues, and counseling referrals to study child development, learning barriers, effectiveness of support programs, and more.

How do I Write a Case Study in Psychology?

Follow specified case study guidelines provided by a journal or your psychology tutor. General components of clinical case studies include: background, symptoms, assessments, diagnosis, treatment, and outcomes. Interpreting the information means the researcher decides what to include or leave out. A good case study should always clarify which information is the factual description and which is an inference or the researcher’s opinion.

1. Introduction

• Provide background on the case context and why it is of interest, presenting background information like demographics, relevant history, and presenting problem.
• Compare briefly to similar published cases if applicable. Clearly state the focus/importance of the case.

2. Case Presentation

• Describe the presenting problem in detail, including symptoms, duration,and impact on daily life.
• Include client demographics like age and gender, information about social relationships, and mental health history.
• Describe all physical, emotional, and/or sensory symptoms reported by the client.
• Use patient quotes to describe the initial complaint verbatim. Follow with full-sentence summaries of relevant history details gathered, including key components that led to a working diagnosis.
• Summarize clinical exam results, namely orthopedic/neurological tests, imaging, lab tests, etc. Note actual results rather than subjective conclusions. Provide images if clearly reproducible/anonymized.
• Clearly state the working diagnosis or clinical impression before transitioning to management.

3. Management and Outcome

• Indicate the total duration of care and number of treatments given over what timeframe. Use specific names/descriptions for any therapies/interventions applied.
• Present the results of the intervention,including any quantitative or qualitative data collected.
• For outcomes, utilize visual analog scales for pain, medication usage logs, etc., if possible. Include patient self-reports of improvement/worsening of symptoms. Note the reason for discharge/end of care.

4. Discussion

• Analyze the case, exploring contributing factors, limitations of the study, and connections to existing research.
• Analyze the effectiveness of the intervention,considering factors like participant adherence, limitations of the study, and potential alternative explanations for the results.
• Identify any questions raised in the case analysis and relate insights to established theories and current research if applicable. Avoid definitive claims about physiological explanations.
• Offer clinical implications, and suggest future research directions.

5. Additional Items

• Thank specific assistants for writing support only. No patient acknowledgments.
• References should directly support any key claims or quotes included.
• Use tables/figures/images only if substantially informative. Include permissions and legends/explanatory notes.
• Provides detailed (rich qualitative) information.
• Provides insight for further research.
• Permitting investigation of otherwise impractical (or unethical) situations.

Case studies allow a researcher to investigate a topic in far more detail than might be possible if they were trying to deal with a large number of research participants (nomothetic approach) with the aim of ‘averaging’.

Because of their in-depth, multi-sided approach, case studies often shed light on aspects of human thinking and behavior that would be unethical or impractical to study in other ways.

Research that only looks into the measurable aspects of human behavior is not likely to give us insights into the subjective dimension of experience, which is important to psychoanalytic and humanistic psychologists.

Case studies are often used in exploratory research. They can help us generate new ideas (that might be tested by other methods). They are an important way of illustrating theories and can help show how different aspects of a person’s life are related to each other.

The method is, therefore, important for psychologists who adopt a holistic point of view (i.e., humanistic psychologists ).

Limitations

• Lacking scientific rigor and providing little basis for generalization of results to the wider population.
• Researchers’ own subjective feelings may influence the case study (researcher bias).
• Difficult to replicate.
• Time-consuming and expensive.
• The volume of data, together with the time restrictions in place, impacted the depth of analysis that was possible within the available resources.

Because a case study deals with only one person/event/group, we can never be sure if the case study investigated is representative of the wider body of “similar” instances. This means the conclusions drawn from a particular case may not be transferable to other settings.

Because case studies are based on the analysis of qualitative (i.e., descriptive) data , a lot depends on the psychologist’s interpretation of the information she has acquired.

This means that there is a lot of scope for Anna O , and it could be that the subjective opinions of the psychologist intrude in the assessment of what the data means.

For example, Freud has been criticized for producing case studies in which the information was sometimes distorted to fit particular behavioral theories (e.g., Little Hans ).

This is also true of Money’s interpretation of the Bruce/Brenda case study (Diamond, 1997) when he ignored evidence that went against his theory.

Breuer, J., & Freud, S. (1895).  Studies on hysteria . Standard Edition 2: London.

Curtiss, S. (1981). Genie: The case of a modern wild child .

Diamond, M., & Sigmundson, K. (1997). Sex Reassignment at Birth: Long-term Review and Clinical Implications. Archives of Pediatrics & Adolescent Medicine , 151(3), 298-304

Freud, S. (1909a). Analysis of a phobia of a five year old boy. In The Pelican Freud Library (1977), Vol 8, Case Histories 1, pages 169-306

Freud, S. (1909b). Bemerkungen über einen Fall von Zwangsneurose (Der “Rattenmann”). Jb. psychoanal. psychopathol. Forsch ., I, p. 357-421; GW, VII, p. 379-463; Notes upon a case of obsessional neurosis, SE , 10: 151-318.

Harlow J. M. (1848). Passage of an iron rod through the head.  Boston Medical and Surgical Journal, 39 , 389–393.

Harlow, J. M. (1868).  Recovery from the Passage of an Iron Bar through the Head .  Publications of the Massachusetts Medical Society. 2  (3), 327-347.

Money, J., & Ehrhardt, A. A. (1972).  Man & Woman, Boy & Girl : The Differentiation and Dimorphism of Gender Identity from Conception to Maturity. Baltimore, Maryland: Johns Hopkins University Press.

Money, J., & Tucker, P. (1975). Sexual signatures: On being a man or a woman.

Further Information

• Case Study Approach
• Case Study Method
• Enhancing the Quality of Case Studies in Health Services Research
• “We do things together” A case study of “couplehood” in dementia
• Using mixed methods for evaluating an integrative approach to cancer care: a case study

Case Study Research: Methods and Designs

Case study research is a type of qualitative research design. It’s often used in the social sciences because it involves…

Case study research is a type of qualitative research design. It’s often used in the social sciences because it involves observing subjects, or cases, in their natural setting, with minimal interference from the researcher.

In the case study method , researchers pose a specific question about an individual or group to test their theories or hypothesis. This can be done by gathering data from interviews with key informants.

Here’s what you need to know about case study research design .

What Is The Case Study Method?

Main approaches to data collection, case study research methods, how case studies are used, case study model.

Case study research is a great way to understand the nuances of a matter that can get lost in quantitative research methods. A case study is distinct from other qualitative studies in the following ways:

• It’s interested in the effect of a set of circumstances on an individual or group.
• It begins with a specific question about one or more cases.
• It focuses on individual accounts and experiences.

Here are the primary features of case study research:

• Case study research methods typically involve the researcher asking a few questions of one person or a small number of people—known as respondents—to test one hypothesis.
• Case study in research methodology may apply triangulation to collect data, in which the researcher uses several sources, including documents and field data. This is then analyzed and interpreted to form a hypothesis that can be tested through further research or validated by other researchers.
• The case study method requires clear concepts and theories to guide its methods. A well-defined research question is crucial when conducting a case study because the results of the study depend on it. The best approach to answering a research question is to challenge the existing theories, hypotheses or assumptions.
• Concepts are defined using objective language with no reference to preconceived notions that individuals might have about them. The researcher sets out to discover by asking specific questions on how people think or perceive things in their given situation.

They commonly use the case study method in business, management, psychology, sociology, political science and other related fields.

A fundamental requirement of qualitative research is recording observations that provide an understanding of reality. When it comes to the case study method, there are two major approaches that can be used to collect data: document review and fieldwork.

A case study in research methodology also includes literature review, the process by which the researcher collects all data available through historical documents. These might include books, newspapers, journals, videos, photographs and other written material. The researcher may also record information using video cameras to capture events as they occur. The researcher can also go through materials produced by people involved in the case study to gain an insight into their lives and experiences.

Field research involves participating in interviews and observations directly. Observation can be done during telephone interviews, events or public meetings, visits to homes or workplaces, or by shadowing someone for a period of time. The researcher can conduct one-on-one interviews with individuals or group interviews where several people are interviewed at once.

Let’s look now at case study methodology.

The case study method can be divided into three stages: formulation of objectives; collection of data; and analysis and interpretation. The researcher first makes a judgment about what should be studied based on their knowledge. Next, they gather data through observations and interviews. Here are some of the common case study research methods:

One of the most basic methods is the survey. Respondents are asked to complete a questionnaire with open-ended and predetermined questions. It usually takes place through face-to-face interviews, mailed questionnaires or telephone interviews. It can even be done by an online survey.

2. Semi-structured Interview

For case study research a more complex method is the semi-structured interview. This involves the researcher learning about the topic by listening to what others have to say. This usually occurs through one-on-one interviews with the sample. Semi-structured interviews allow for greater flexibility and can obtain information that structured questionnaires can’t.

3. Focus Group Interview

Another method is the focus group interview, where the researcher asks a few people to take part in an open-ended discussion on certain themes or topics. The typical group size is 5–15 people. This method allows researchers to delve deeper into people’s opinions, views and experiences.

4. Participant Observation

Participant observation is another method that involves the researcher gaining insight into an experience by joining in and taking part in normal events. The people involved don’t always know they’re being studied, but the researcher observes and records what happens through field notes.

Case study research design can use one or several of these methods depending on the context.

Case studies are widely used in the social sciences. To understand the impact of socio-economic forces, interpersonal dynamics and other human conditions, sometimes there’s no other way than to study one case at a time and look for patterns and data afterward.

It’s for the same reasons that case studies are used in business. Here are a few uses:

• Case studies can be used as tools to educate and give examples of situations and problems that might occur and how they were resolved. They can also be used for strategy development and implementation.
• Case studies can evaluate the success of a program or project. They can help teams improve their collaboration by identifying areas that need improvements, such as team dynamics, communication, roles and responsibilities and leadership styles.
• Case studies can explore how people’s experiences affect the working environment. Because the study involves observing and analyzing concrete details of life, they can inform theories on how an individual or group interacts with their environment.
• Case studies can evaluate the sustainability of businesses. They’re useful for social, environmental and economic impact studies because they look at all aspects of a business or organization. This gives researchers a holistic view of the dynamics within an organization.
• We can use case studies to identify problems in organizations or businesses. They can help spot problems that are invisible to customers, investors, managers and employees.
• Case studies are used in education to show students how real-world issues or events can be sorted out. This enables students to identify and deal with similar situations in their lives.

And that’s not all. Case studies are incredibly versatile, which is why they’re used so widely.

Human beings are complex and they interact with each other in their everyday life in various ways. The researcher observes a case and tries to find out how the patterns of behavior are created, including their causal relations. Case studies help understand one or more specific events that have been observed. Here are some common methods:

1. Illustrative case study

This is where the researcher observes a group of people doing something. Studying an event or phenomenon this way can show cause-and-effect relationships between various variables.

2. Cumulative case study

A cumulative case study is one that involves observing the same set of phenomena over a period. Cumulative case studies can be very helpful in understanding processes, which are things that happen over time. For example, if there are behavioral changes in people who move from one place to another, the researcher might want to know why these changes occurred.

3. Exploratory case study

An exploratory case study collects information that will answer a question. It can help researchers better understand social, economic, political or other social phenomena.

There are several other ways to categorize case studies. They may be chronological case studies, where a researcher observes events over time. In the comparative case study, the researcher compares one or more groups of people, places, or things to draw conclusions about them. In an intervention case study, the researcher intervenes to change the behavior of the subjects. The study method depends on the needs of the research team.

Deciding how to analyze the information at our disposal is an important part of effective management. An understanding of the case study model can help. With Harappa’s Thinking Critically course, managers and young professionals receive input and training on how to level up their analytic skills. Knowledge of frameworks, reading real-life examples and lived wisdom of faculty come together to create a dynamic and exciting course that helps teams leap to the next level.

Explore Harappa Diaries to learn more about topics such as Objectives Of Research , What are Qualitative Research Methods , How To Make A Problem Statement and How To Improve your Cognitive Skills to upgrade your knowledge and skills.

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5 Benefits of Learning Through the Case Study Method

• 28 Nov 2023

While several factors make HBS Online unique —including a global Community and real-world outcomes —active learning through the case study method rises to the top.

In a 2023 City Square Associates survey, 74 percent of HBS Online learners who also took a course from another provider said HBS Online’s case method and real-world examples were better by comparison.

Here’s a primer on the case method, five benefits you could gain, and how to experience it for yourself.

Access your free e-book today.

What Is the Harvard Business School Case Study Method?

The case study method , or case method , is a learning technique in which you’re presented with a real-world business challenge and asked how you’d solve it. After working through it yourself and with peers, you’re told how the scenario played out.

HBS pioneered the case method in 1922. Shortly before, in 1921, the first case was written.

“How do you go into an ambiguous situation and get to the bottom of it?” says HBS Professor Jan Rivkin, former senior associate dean and chair of HBS's master of business administration (MBA) program, in a video about the case method . “That skill—the skill of figuring out a course of inquiry to choose a course of action—that skill is as relevant today as it was in 1921.”

Originally developed for the in-person MBA classroom, HBS Online adapted the case method into an engaging, interactive online learning experience in 2014.

In HBS Online courses , you learn about each case from the business professional who experienced it. After reviewing their videos, you’re prompted to take their perspective and explain how you’d handle their situation.

You then get to read peers’ responses, “star” them, and comment to further the discussion. Afterward, you learn how the professional handled it and their key takeaways.

Learn more about HBS Online's approach to the case method in the video below, and subscribe to our YouTube channel for more.

HBS Online’s adaptation of the case method incorporates the famed HBS “cold call,” in which you’re called on at random to make a decision without time to prepare.

“Learning came to life!” said Sheneka Balogun , chief administration officer and chief of staff at LeMoyne-Owen College, of her experience taking the Credential of Readiness (CORe) program . “The videos from the professors, the interactive cold calls where you were randomly selected to participate, and the case studies that enhanced and often captured the essence of objectives and learning goals were all embedded in each module. This made learning fun, engaging, and student-friendly.”

If you’re considering taking a course that leverages the case study method, here are five benefits you could experience.

5 Benefits of Learning Through Case Studies

1. take new perspectives.

The case method prompts you to consider a scenario from another person’s perspective. To work through the situation and come up with a solution, you must consider their circumstances, limitations, risk tolerance, stakeholders, resources, and potential consequences to assess how to respond.

Taking on new perspectives not only can help you navigate your own challenges but also others’. Putting yourself in someone else’s situation to understand their motivations and needs can go a long way when collaborating with stakeholders.

2. Hone Your Decision-Making Skills

Another skill you can build is the ability to make decisions effectively . The case study method forces you to use limited information to decide how to handle a problem—just like in the real world.

Throughout your career, you’ll need to make difficult decisions with incomplete or imperfect information—and sometimes, you won’t feel qualified to do so. Learning through the case method allows you to practice this skill in a low-stakes environment. When facing a real challenge, you’ll be better prepared to think quickly, collaborate with others, and present and defend your solution.

3. Become More Open-Minded

As you collaborate with peers on responses, it becomes clear that not everyone solves problems the same way. Exposing yourself to various approaches and perspectives can help you become a more open-minded professional.

When you’re part of a diverse group of learners from around the world, your experiences, cultures, and backgrounds contribute to a range of opinions on each case.

On the HBS Online course platform, you’re prompted to view and comment on others’ responses, and discussion is encouraged. This practice of considering others’ perspectives can make you more receptive in your career.

“You’d be surprised at how much you can learn from your peers,” said Ratnaditya Jonnalagadda , a software engineer who took CORe.

In addition to interacting with peers in the course platform, Jonnalagadda was part of the HBS Online Community , where he networked with other professionals and continued discussions sparked by course content.

“You get to understand your peers better, and students share examples of businesses implementing a concept from a module you just learned,” Jonnalagadda said. “It’s a very good way to cement the concepts in one's mind.”

4. Enhance Your Curiosity

One byproduct of taking on different perspectives is that it enables you to picture yourself in various roles, industries, and business functions.

“Each case offers an opportunity for students to see what resonates with them, what excites them, what bores them, which role they could imagine inhabiting in their careers,” says former HBS Dean Nitin Nohria in the Harvard Business Review . “Cases stimulate curiosity about the range of opportunities in the world and the many ways that students can make a difference as leaders.”

Through the case method, you can “try on” roles you may not have considered and feel more prepared to change or advance your career .

5. Build Your Self-Confidence

Finally, learning through the case study method can build your confidence. Each time you assume a business leader’s perspective, aim to solve a new challenge, and express and defend your opinions and decisions to peers, you prepare to do the same in your career.

According to a 2022 City Square Associates survey , 84 percent of HBS Online learners report feeling more confident making business decisions after taking a course.

“Self-confidence is difficult to teach or coach, but the case study method seems to instill it in people,” Nohria says in the Harvard Business Review . “There may well be other ways of learning these meta-skills, such as the repeated experience gained through practice or guidance from a gifted coach. However, under the direction of a masterful teacher, the case method can engage students and help them develop powerful meta-skills like no other form of teaching.”

How to Experience the Case Study Method

If the case method seems like a good fit for your learning style, experience it for yourself by taking an HBS Online course. Offerings span eight subject areas, including:

• Business essentials
• Leadership and management
• Entrepreneurship and innovation
• Digital transformation
• Finance and accounting
• Business in society

No matter which course or credential program you choose, you’ll examine case studies from real business professionals, work through their challenges alongside peers, and gain valuable insights to apply to your career.

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About the Author

What is the Case Study Method?

Simply put, the case method is a discussion of real-life situations that business executives have faced.

On average, you'll attend three to four different classes a day, for a total of about six hours of class time (schedules vary). To prepare, you'll work through problems with your peers.

How the Case Method Creates Value

Often, executives are surprised to discover that the objective of the case study is not to reach consensus, but to understand how different people use the same information to arrive at diverse conclusions. When you begin to understand the context, you can appreciate the reasons why those decisions were made. You can prepare for case discussions in several ways.

Case Discussion Preparation Details

In self-reflection.

The time you spend here is deeply introspective. You're not only working with case materials and assignments, but also taking on the role of the case protagonist—the person who's supposed to make those tough decisions. How would you react in those situations? We put people in a variety of contexts, and they start by addressing that specific problem.

In a small group setting

The discussion group is a critical component of the HBS experience. You're working in close quarters with a group of seven or eight very accomplished peers in diverse functions, industries, and geographies. Because they bring unique experience to play you begin to see that there are many different ways to wrestle with a problem—and that’s very enriching.

In the classroom

The faculty guides you in examining and resolving the issues—but the beauty here is that they don't provide you with the answers. You're interacting in the classroom with other executives—debating the issue, presenting new viewpoints, countering positions, and building on one another's ideas. And that leads to the next stage of learning.

Beyond the classroom

Once you leave the classroom, the learning continues and amplifies as you get to know people in different settings—over meals, at social gatherings, in the fitness center, or as you are walking to class. You begin to distill the takeaways that you want to bring back and apply in your organization to ensure that the decisions you make will create more value for your firm.

How Cases Unfold In the Classroom

Pioneered by HBS faculty, the case method puts you in the role of the chief decision maker as you explore the challenges facing leading companies across the globe. Learning to think fast on your feet with limited information sharpens your analytical skills and empowers you to make critical decisions in real time.

To get the most out of each case, it's important to read and reflect, and then meet with your discussion group to share your insights. You and your peers will explore the underlying issues, compare alternatives, and suggest various ways of resolving the problem.

How to Prepare for Case Discussions

There's more than one way to prepare for a case discussion, but these general guidelines can help you develop a method that works for you.

Preparation Guidelines

Read the professor's assignment or discussion questions.

The assignment and discussion questions help you focus on the key aspects of the case. Ask yourself: What are the most important issues being raised?

Read the first few paragraphs and then skim the case

Each case begins with a text description followed by exhibits. Ask yourself: What is the case generally about, and what information do I need to analyze?

Reread the case, underline text, and make margin notes

Put yourself in the shoes of the case protagonist, and own that person's problems. Ask yourself: What basic problem is this executive trying to resolve?

Note the key problems on a pad of paper and go through the case again

Sort out relevant considerations and do the quantitative or qualitative analysis. Ask yourself: What recommendations should I make based on my case data analysis?

Case Study Best Practices

The key to being an active listener and participant in case discussions—and to getting the most out of the learning experience—is thorough individual preparation.

We've set aside formal time for you to discuss the case with your group. These sessions will help you to become more confident about sharing your views in the classroom discussion.

Participate

Actively express your views and challenge others. Don't be afraid to share related "war stories" that will heighten the relevance and enrich the discussion.

If the content doesn't seem to relate to your business, don't tune out. You can learn a lot about marketing insurance from a case on marketing razor blades!

Actively apply what you're learning to your own specific management situations, both past and future. This will magnify the relevance to your business.

People with diverse backgrounds, experiences, skills, and styles will take away different things. Be sure to note what resonates with you, not your peers.

Being exposed to so many different approaches to a given situation will put you in a better position to enhance your management style.

Frequently Asked Questions

What can i expect on the first day, what happens in class if nobody talks, does everyone take part in "role-playing".

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Methodologic and Data-Analysis Triangulation in Case Studies: A Scoping Review

Margarithe charlotte schlunegger.

1 Department of Health Professions, Applied Research & Development in Nursing, Bern University of Applied Sciences, Bern, Switzerland

2 Faculty of Health, School of Nursing Science, Witten/Herdecke University, Witten, Germany

Maya Zumstein-Shaha

Rebecca palm.

3 Department of Health Care Research, Carl von Ossietzky University Oldenburg, Oldenburg, Germany

Associated Data

Supplemental material, sj-docx-1-wjn-10.1177_01939459241263011 for Methodologic and Data-Analysis Triangulation in Case Studies: A Scoping Review by Margarithe Charlotte Schlunegger, Maya Zumstein-Shaha and Rebecca Palm in Western Journal of Nursing Research

We sought to explore the processes of methodologic and data-analysis triangulation in case studies using the example of research on nurse practitioners in primary health care.

Design and methods:

We conducted a scoping review within Arksey and O’Malley’s methodological framework, considering studies that defined a case study design and used 2 or more data sources, published in English or German before August 2023.

Data sources:

The databases searched were MEDLINE and CINAHL, supplemented with hand searching of relevant nursing journals. We also examined the reference list of all the included studies.

In total, 63 reports were assessed for eligibility. Ultimately, we included 8 articles. Five studies described within-method triangulation, whereas 3 provided information on between/across-method triangulation. No study reported within-method triangulation of 2 or more quantitative data-collection procedures. The data-collection procedures were interviews, observation, documentation/documents, service records, and questionnaires/assessments. The data-analysis triangulation involved various qualitative and quantitative methods of analysis. Details about comparing or contrasting results from different qualitative and mixed-methods data were lacking.

Conclusions:

Various processes for methodologic and data-analysis triangulation are described in this scoping review but lack detail, thus hampering standardization in case study research, potentially affecting research traceability. Triangulation is complicated by terminological confusion. To advance case study research in nursing, authors should reflect critically on the processes of triangulation and employ existing tools, like a protocol or mixed-methods matrix, for transparent reporting. The only existing reporting guideline should be complemented with directions on methodologic and data-analysis triangulation.

Case study research is defined as “an empirical method that investigates a contemporary phenomenon (the ‘case’) in depth and within its real-world context, especially when the boundaries between phenomenon and context may not be clearly evident. A case study relies on multiple sources of evidence, with data needing to converge in a triangulating fashion.” 1 (p15) This design is described as a stand-alone research approach equivalent to grounded theory and can entail single and multiple cases. 1 , 2 However, case study research should not be confused with single clinical case reports. “Case reports are familiar ways of sharing events of intervening with single patients with previously unreported features.” 3 (p107) As a methodology, case study research encompasses substantially more complexity than a typical clinical case report. 1 , 3

A particular characteristic of case study research is the use of various data sources, such as quantitative data originating from questionnaires as well as qualitative data emerging from interviews, observations, or documents. Therefore, a case study always draws on multiple sources of evidence, and the data must converge in a triangulating manner. 1 When using multiple data sources, a case or cases can be examined more convincingly and accurately, compensating for the weaknesses of the respective data sources. 1 Another characteristic is the interaction of various perspectives. This involves comparing or contrasting perspectives of people with different points of view, eg, patients, staff, or leaders. 4 Through triangulation, case studies contribute to the completeness of the research on complex topics, such as role implementation in clinical practice. 1 , 5 Triangulation involves a combination of researchers from various disciplines, of theories, of methods, and/or of data sources. By creating connections between these sources (ie, investigator, theories, methods, data sources, and/or data analysis), a new understanding of the phenomenon under study can be obtained. 6 , 7

This scoping review focuses on methodologic and data-analysis triangulation because concrete procedures are missing, eg, in reporting guidelines. Methodologic triangulation has been called methods, mixed methods, or multimethods. 6 It can encompass within-method triangulation and between/across-method triangulation. 7 “Researchers using within-method triangulation use at least 2 data-collection procedures from the same design approach.” 6 (p254) Within-method triangulation is either qualitative or quantitative but not both. Therefore, within-method triangulation can also be considered data source triangulation. 8 In contrast, “researchers using between/across-method triangulation employ both qualitative and quantitative data-collection methods in the same study.” 6 (p254) Hence, methodologic approaches are combined as well as various data sources. For this scoping review, the term “methodologic triangulation” is maintained to denote between/across-method triangulation. “Data-analysis triangulation is the combination of 2 or more methods of analyzing data.” 6 (p254)

Although much has been published on case studies, there is little consensus on the quality of the various data sources, the most appropriate methods, or the procedures for conducting methodologic and data-analysis triangulation. 5 According to the EQUATOR (Enhancing the QUAlity and Transparency Of health Research) clearinghouse for reporting guidelines, one standard exists for organizational case studies. 9 Organizational case studies provide insights into organizational change in health care services. 9 Rodgers et al 9 pointed out that, although high-quality studies are being funded and published, they are sometimes poorly articulated and methodologically inadequate. In the reporting checklist by Rodgers et al, 9 a description of the data collection is included, but reporting directions on methodologic and data-analysis triangulation are missing. Therefore, the purpose of this study was to examine the process of methodologic and data-analysis triangulation in case studies. Accordingly, we conducted a scoping review to elicit descriptions of and directions for triangulation methods and analysis, drawing on case studies of nurse practitioners (NPs) in primary health care as an example. Case studies are recommended to evaluate the implementation of new roles in (primary) health care, such as that of NPs. 1 , 5 Case studies on new role implementation can generate a unique and in-depth understanding of specific roles (individual), teams (smaller groups), family practices or similar institutions (organization), and social and political processes in health care systems. 1 , 10 The integration of NPs into health care systems is at different stages of progress around the world. 11 Therefore, studies are needed to evaluate this process.

The methodological framework by Arksey and O’Malley 12 guided this scoping review. We examined the current scientific literature on the use of methodologic and data-analysis triangulation in case studies on NPs in primary health care. The review process included the following stages: (1) establishing the research question; (2) identifying relevant studies; (3) selecting the studies for inclusion; (4) charting the data; (5) collating, summarizing, and reporting the results; and (6) consulting experts in the field. 12 Stage 6 was not performed due to a lack of financial resources. The reporting of the review followed the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Review) guideline by Tricco et al 13 (guidelines for reporting systematic reviews and meta-analyses [ Supplementary Table A ]). Scoping reviews are not eligible for registration in PROSPERO.

Stage 1: Establishing the Research Question

The aim of this scoping review was to examine the process of triangulating methods and analysis in case studies on NPs in primary health care to improve the reporting. We sought to answer the following question: How have methodologic and data-analysis triangulation been conducted in case studies on NPs in primary health care? To answer the research question, we examined the following elements of the selected studies: the research question, the study design, the case definition, the selected data sources, and the methodologic and data-analysis triangulation.

Stage 2: Identifying Relevant Studies

A systematic database search was performed in the MEDLINE (via PubMed) and CINAHL (via EBSCO) databases between July and September 2020 to identify relevant articles. The following terms were used as keyword search strategies: (“Advanced Practice Nursing” OR “nurse practitioners”) AND (“primary health care” OR “Primary Care Nursing”) AND (“case study” OR “case studies”). Searches were limited to English- and German-language articles. Hand searches were conducted in the journals Nursing Inquiry , BMJ Open , and BioMed Central ( BMC ). We also screened the reference lists of the studies included. The database search was updated in August 2023. The complete search strategy for all the databases is presented in Supplementary Table B .

Stage 3: Selecting the Studies

Inclusion and exclusion criteria.

We used the inclusion and exclusion criteria reported in Table 1 . We included studies of NPs who had at least a master’s degree in nursing according to the definition of the International Council of Nurses. 14 This scoping review considered studies that were conducted in primary health care practices in rural, urban, and suburban regions. We excluded reviews and study protocols in which no data collection had occurred. Articles were included without limitations on the time period or country of origin.

Inclusion and Exclusion Criteria.

Screening process

After the search, we collated and uploaded all the identified records into EndNote v.X8 (Clarivate Analytics, Philadelphia, Pennsylvania) and removed any duplicates. Two independent reviewers (MCS and SA) screened the titles and abstracts for assessment in line with the inclusion criteria. They retrieved and assessed the full texts of the selected studies while applying the inclusion criteria. Any disagreements about the eligibility of studies were resolved by discussion or, if no consensus could be reached, by involving experienced researchers (MZ-S and RP).

Stages 4 and 5: Charting the Data and Collating, Summarizing, and Reporting the Results

The first reviewer (MCS) extracted data from the selected publications. For this purpose, an extraction tool developed by the authors was used. This tool comprised the following criteria: author(s), year of publication, country, research question, design, case definition, data sources, and methodologic and data-analysis triangulation. First, we extracted and summarized information about the case study design. Second, we narratively summarized the way in which the data and methodological triangulation were described. Finally, we summarized the information on within-case or cross-case analysis. This process was performed using Microsoft Excel. One reviewer (MCS) extracted data, whereas another reviewer (SA) cross-checked the data extraction, making suggestions for additions or edits. Any disagreements between the reviewers were resolved through discussion.

A total of 149 records were identified in 2 databases. We removed 20 duplicates and screened 129 reports by title and abstract. A total of 46 reports were assessed for eligibility. Through hand searches, we identified 117 additional records. Of these, we excluded 98 reports after title and abstract screening. A total of 17 reports were assessed for eligibility. From the 2 databases and the hand search, 63 reports were assessed for eligibility. Ultimately, we included 8 articles for data extraction. No further articles were included after the reference list screening of the included studies. A PRISMA flow diagram of the study selection and inclusion process is presented in Figure 1 . As shown in Tables 2 and ​ and3, 3 , the articles included in this scoping review were published between 2010 and 2022 in Canada (n = 3), the United States (n = 2), Australia (n = 2), and Scotland (n = 1).

PRISMA flow diagram.

Characteristics of Articles Included.

Overview of Within-Method, Between/Across-Method, and Data-Analysis Triangulation.

Research Question, Case Definition, and Case Study Design

The following sections describe the research question, case definition, and case study design. Case studies are most appropriate when asking “how” or “why” questions. 1 According to Yin, 1 how and why questions are explanatory and lead to the use of case studies, histories, and experiments as the preferred research methods. In 1 study from Canada, eg, the following research question was presented: “How and why did stakeholders participate in the system change process that led to the introduction of the first nurse practitioner-led Clinic in Ontario?” (p7) 19 Once the research question has been formulated, the case should be defined and, subsequently, the case study design chosen. 1 In typical case studies with mixed methods, the 2 types of data are gathered concurrently in a convergent design and the results merged to examine a case and/or compare multiple cases. 10

Research question

“How” or “why” questions were found in 4 studies. 16 , 17 , 19 , 22 Two studies additionally asked “what” questions. Three studies described an exploratory approach, and 1 study presented an explanatory approach. Of these 4 studies, 3 studies chose a qualitative approach 17 , 19 , 22 and 1 opted for mixed methods with a convergent design. 16

In the remaining studies, either the research questions were not clearly stated or no “how” or “why” questions were formulated. For example, “what” questions were found in 1 study. 21 No information was provided on exploratory, descriptive, and explanatory approaches. Schadewaldt et al 21 chose mixed methods with a convergent design.

Case definition and case study design

A total of 5 studies defined the case as an organizational unit. 17 , 18 - 20 , 22 Of the 8 articles, 4 reported multiple-case studies. 16 , 17 , 22 , 23 Another 2 publications involved single-case studies. 19 , 20 Moreover, 2 publications did not state the case study design explicitly.

Within-Method Triangulation

This section describes within-method triangulation, which involves employing at least 2 data-collection procedures within the same design approach. 6 , 7 This can also be called data source triangulation. 8 Next, we present the single data-collection procedures in detail. In 5 studies, information on within-method triangulation was found. 15 , 17 - 19 , 22 Studies describing a quantitative approach and the triangulation of 2 or more quantitative data-collection procedures could not be included in this scoping review.

Qualitative approach

Five studies used qualitative data-collection procedures. Two studies combined face-to-face interviews and documents. 15 , 19 One study mixed in-depth interviews with observations, 18 and 1 study combined face-to-face interviews and documentation. 22 One study contained face-to-face interviews, observations, and documentation. 17 The combination of different qualitative data-collection procedures was used to present the case context in an authentic and complex way, to elicit the perspectives of the participants, and to obtain a holistic description and explanation of the cases under study.

All 5 studies used qualitative interviews as the primary data-collection procedure. 15 , 17 - 19 , 22 Face-to-face, in-depth, and semi-structured interviews were conducted. The topics covered in the interviews included processes in the introduction of new care services and experiences of barriers and facilitators to collaborative work in general practices. Two studies did not specify the type of interviews conducted and did not report sample questions. 15 , 18

Observations

In 2 studies, qualitative observations were carried out. 17 , 18 During the observations, the physical design of the clinical patients’ rooms and office spaces was examined. 17 Hungerford et al 18 did not explain what information was collected during the observations. In both studies, the type of observation was not specified. Observations were generally recorded as field notes.

Public documents

In 3 studies, various qualitative public documents were studied. 15 , 19 , 22 These documents included role description, education curriculum, governance frameworks, websites, and newspapers with information about the implementation of the role and general practice. Only 1 study failed to specify the type of document and the collected data. 15

Electronic health records

In 1 study, qualitative documentation was investigated. 17 This included a review of dashboards (eg, provider productivity reports or provider quality dashboards in the electronic health record) and quality performance reports (eg, practice-wide or co-management team-wide performance reports).

Between/Across-Method Triangulation

This section describes the between/across methods, which involve employing both qualitative and quantitative data-collection procedures in the same study. 6 , 7 This procedure can also be denoted “methodologic triangulation.” 8 Subsequently, we present the individual data-collection procedures. In 3 studies, information on between/across triangulation was found. 16 , 20 , 21

Mixed methods

Three studies used qualitative and quantitative data-collection procedures. One study combined face-to-face interviews, documentation, and self-assessments. 16 One study employed semi-structured interviews, direct observation, documents, and service records, 20 and another study combined face-to-face interviews, non-participant observation, documents, and questionnaires. 23

All 3 studies used qualitative interviews as the primary data-collection procedure. 16 , 20 , 23 Face-to-face and semi-structured interviews were conducted. In the interviews, data were collected on the introduction of new care services and experiences of barriers to and facilitators of collaborative work in general practices.

Observation

In 2 studies, direct and non-participant qualitative observations were conducted. 20 , 23 During the observations, the interaction between health professionals or the organization and the clinical context was observed. Observations were generally recorded as field notes.

In 2 studies, various qualitative public documents were examined. 20 , 23 These documents included role description, newspapers, websites, and practice documents (eg, flyers). In the documents, information on the role implementation and role description of NPs was collected.

Individual journals

In 1 study, qualitative individual journals were studied. 16 These included reflective journals from NPs, who performed the role in primary health care.

Service records

Only 1 study involved quantitative service records. 20 These service records were obtained from the primary care practices and the respective health authorities. They were collected before and after the implementation of an NP role to identify changes in patients’ access to health care, the volume of patients served, and patients’ use of acute care services.

Questionnaires/Assessment

In 2 studies, quantitative questionnaires were used to gather information about the teams’ satisfaction with collaboration. 16 , 21 In 1 study, 3 validated scales were used. The scales measured experience, satisfaction, and belief in the benefits of collaboration. 21 Psychometric performance indicators of these scales were provided. However, the time points of data collection were not specified; similarly, whether the questionnaires were completed online or by hand was not mentioned. A competency self-assessment tool was used in another study. 16 The assessment comprised 70 items and included topics such as health promotion, protection, disease prevention and treatment, the NP-patient relationship, the teaching-coaching function, the professional role, managing and negotiating health care delivery systems, monitoring and ensuring the quality of health care practice, and cultural competence. Psychometric performance indicators were provided. The assessment was completed online with 2 measurement time points (pre self-assessment and post self-assessment).

Data-Analysis Triangulation

This section describes data-analysis triangulation, which involves the combination of 2 or more methods of analyzing data. 6 Subsequently, we present within-case analysis and cross-case analysis.

Mixed-methods analysis

Three studies combined qualitative and quantitative methods of analysis. 16 , 20 , 21 Two studies involved deductive and inductive qualitative analysis, and qualitative data were analyzed thematically. 20 , 21 One used deductive qualitative analysis. 16 The method of analysis was not specified in the studies. Quantitative data were analyzed using descriptive statistics in 3 studies. 16 , 20 , 23 The descriptive statistics comprised the calculation of the mean, median, and frequencies.

Qualitative methods of analysis

Two studies combined deductive and inductive qualitative analysis, 19 , 22 and 2 studies only used deductive qualitative analysis. 15 , 18 Qualitative data were analyzed thematically in 1 study, 22 and data were treated with content analysis in the other. 19 The method of analysis was not specified in the 2 studies.

Within-case analysis

In 7 studies, a within-case analysis was performed. 15 - 20 , 22 Six studies used qualitative data for the within-case analysis, and 1 study employed qualitative and quantitative data. Data were analyzed separately, consecutively, or in parallel. The themes generated from qualitative data were compared and then summarized. The individual cases were presented mostly as a narrative description. Quantitative data were integrated into the qualitative description with tables and graphs. Qualitative and quantitative data were also presented as a narrative description.

Cross-case analyses

Of the multiple-case studies, 5 carried out cross-case analyses. 15 - 17 , 20 , 22 Three studies described the cross-case analysis using qualitative data. Two studies reported a combination of qualitative and quantitative data for the cross-case analysis. In each multiple-case study, the individual cases were contrasted to identify the differences and similarities between the cases. One study did not specify whether a within-case or a cross-case analysis was conducted. 23

Confirmation or contradiction of data

This section describes confirmation or contradiction through qualitative and quantitative data. 1 , 4 Qualitative and quantitative data were reported separately, with little connection between them. As a result, the conclusions on neither the comparisons nor the contradictions could be clearly determined.

Confirmation or contradiction among qualitative data

In 3 studies, the consistency of the results of different types of qualitative data was highlighted. 16 , 19 , 21 In particular, documentation and interviews or interviews and observations were contrasted:

• Confirmation between interviews and documentation: The data from these sources corroborated the existence of a common vision for an NP-led clinic. 19
• Confirmation among interviews and observation: NPs experienced pressure to find and maintain their position within the existing system. Nurse practitioners and general practitioners performed complete episodes of care, each without collaborative interaction. 21
• Contradiction among interviews and documentation: For example, interviewees mentioned that differentiating the scope of practice between NPs and physicians is difficult as there are too many areas of overlap. However, a clear description of the scope of practice for the 2 roles was provided. 21

Confirmation through a combination of qualitative and quantitative data

Both types of data showed that NPs and general practitioners wanted to have more time in common to discuss patient cases and engage in personal exchanges. 21 In addition, the qualitative and quantitative data confirmed the individual progression of NPs from less competent to more competent. 16 One study pointed out that qualitative and quantitative data obtained similar results for the cases. 20 For example, integrating NPs improved patient access by increasing appointment availability.

Contradiction through a combination of qualitative and quantitative data

Although questionnaire results indicated that NPs and general practitioners experienced high levels of collaboration and satisfaction with the collaborative relationship, the qualitative results drew a more ambivalent picture of NPs’ and general practitioners’ experiences with collaboration. 21

Research Question and Design

The studies included in this scoping review evidenced various research questions. The recommended formats (ie, how or why questions) were not applied consistently. Therefore, no case study design should be applied because the research question is the major guide for determining the research design. 2 Furthermore, case definitions and designs were applied variably. The lack of standardization is reflected in differences in the reporting of these case studies. Generally, case study research is viewed as allowing much more freedom and flexibility. 5 , 24 However, this flexibility and the lack of uniform specifications lead to confusion.

Methodologic Triangulation

Methodologic triangulation, as described in the literature, can be somewhat confusing as it can refer to either data-collection methods or research designs. 6 , 8 For example, methodologic triangulation can allude to qualitative and quantitative methods, indicating a paradigmatic connection. Methodologic triangulation can also point to qualitative and quantitative data-collection methods, analysis, and interpretation without specific philosophical stances. 6 , 8 Regarding “data-collection methods with no philosophical stances,” we would recommend using the wording “data source triangulation” instead. Thus, the demarcation between the method and the data-collection procedures will be clearer.

Within-Method and Between/Across-Method Triangulation

Yin 1 advocated the use of multiple sources of evidence so that a case or cases can be investigated more comprehensively and accurately. Most studies included multiple data-collection procedures. Five studies employed a variety of qualitative data-collection procedures, and 3 studies used qualitative and quantitative data-collection procedures (mixed methods). In contrast, no study contained 2 or more quantitative data-collection procedures. In particular, quantitative data-collection procedures—such as validated, reliable questionnaires, scales, or assessments—were not used exhaustively. The prerequisites for using multiple data-collection procedures are availability, the knowledge and skill of the researcher, and sufficient financial funds. 1 To meet these prerequisites, research teams consisting of members with different levels of training and experience are necessary. Multidisciplinary research teams need to be aware of the strengths and weaknesses of different data sources and collection procedures. 1

Qualitative methods of analysis and results

When using multiple data sources and analysis methods, it is necessary to present the results in a coherent manner. Although the importance of multiple data sources and analysis has been emphasized, 1 , 5 the description of triangulation has tended to be brief. Thus, traceability of the research process is not always ensured. The sparse description of the data-analysis triangulation procedure may be due to the limited number of words in publications or the complexity involved in merging the different data sources.

Only a few concrete recommendations regarding the operationalization of the data-analysis triangulation with the qualitative data process were found. 25 A total of 3 approaches have been proposed 25 : (1) the intuitive approach, in which researchers intuitively connect information from different data sources; (2) the procedural approach, in which each comparative or contrasting step in triangulation is documented to ensure transparency and replicability; and (3) the intersubjective approach, which necessitates a group of researchers agreeing on the steps in the triangulation process. For each case study, one of these 3 approaches needs to be selected, carefully carried out, and documented. Thus, in-depth examination of the data can take place. Farmer et al 25 concluded that most researchers take the intuitive approach; therefore, triangulation is not clearly articulated. This trend is also evident in our scoping review.

Mixed-methods analysis and results

Few studies in this scoping review used a combination of qualitative and quantitative analysis. However, creating a comprehensive stand-alone picture of a case from both qualitative and quantitative methods is challenging. Findings derived from different data types may not automatically coalesce into a coherent whole. 4 O’Cathain et al 26 described 3 techniques for combining the results of qualitative and quantitative methods: (1) developing a triangulation protocol; (2) following a thread by selecting a theme from 1 component and following it across the other components; and (3) developing a mixed-methods matrix.

The most detailed description of the conducting of triangulation is the triangulation protocol. The triangulation protocol takes place at the interpretation stage of the research process. 26 This protocol was developed for multiple qualitative data but can also be applied to a combination of qualitative and quantitative data. 25 , 26 It is possible to determine agreement, partial agreement, “silence,” or dissonance between the results of qualitative and quantitative data. The protocol is intended to bring together the various themes from the qualitative and quantitative results and identify overarching meta-themes. 25 , 26

The “following a thread” technique is used in the analysis stage of the research process. To begin, each data source is analyzed to identify the most important themes that need further investigation. Subsequently, the research team selects 1 theme from 1 data source and follows it up in the other data source, thereby creating a thread. The individual steps of this technique are not specified. 26 , 27

A mixed-methods matrix is used at the end of the analysis. 26 All the data collected on a defined case are examined together in 1 large matrix, paying attention to cases rather than variables or themes. In a mixed-methods matrix (eg, a table), the rows represent the cases for which both qualitative and quantitative data exist. The columns show the findings for each case. This technique allows the research team to look for congruency, surprises, and paradoxes among the findings as well as patterns across multiple cases. In our review, we identified only one of these 3 approaches in the study by Roots and MacDonald. 20 These authors mentioned that a causal network analysis was performed using a matrix. However, no further details were given, and reference was made to a later publication. We could not find this publication.

Case Studies in Nursing Research and Recommendations

Because it focused on the implementation of NPs in primary health care, the setting of this scoping review was narrow. However, triangulation is essential for research in this area. This type of research was found to provide a good basis for understanding methodologic and data-analysis triangulation. Despite the lack of traceability in the description of the data and methodological triangulation, we believe that case studies are an appropriate design for exploring new nursing roles in existing health care systems. This is evidenced by the fact that case study research is widely used in many social science disciplines as well as in professional practice. 1 To strengthen this research method and increase the traceability in the research process, we recommend using the reporting guideline and reporting checklist by Rodgers et al. 9 This reporting checklist needs to be complemented with methodologic and data-analysis triangulation. A procedural approach needs to be followed in which each comparative step of the triangulation is documented. 25 A triangulation protocol or a mixed-methods matrix can be used for this purpose. 26 If there is a word limit in a publication, the triangulation protocol or mixed-methods matrix needs to be identified. A schematic representation of methodologic and data-analysis triangulation in case studies can be found in Figure 2 .

Schematic representation of methodologic and data-analysis triangulation in case studies (own work).

Limitations

This study suffered from several limitations that must be acknowledged. Given the nature of scoping reviews, we did not analyze the evidence reported in the studies. However, 2 reviewers independently reviewed all the full-text reports with respect to the inclusion criteria. The focus on the primary care setting with NPs (master’s degree) was very narrow, and only a few studies qualified. Thus, possible important methodological aspects that would have contributed to answering the questions were omitted. Studies describing the triangulation of 2 or more quantitative data-collection procedures could not be included in this scoping review due to the inclusion and exclusion criteria.

Conclusions

Given the various processes described for methodologic and data-analysis triangulation, we can conclude that triangulation in case studies is poorly standardized. Consequently, the traceability of the research process is not always given. Triangulation is complicated by the confusion of terminology. To advance case study research in nursing, we encourage authors to reflect critically on methodologic and data-analysis triangulation and use existing tools, such as the triangulation protocol or mixed-methods matrix and the reporting guideline checklist by Rodgers et al, 9 to ensure more transparent reporting.

Supplemental Material

Acknowledgments.

The authors thank Simona Aeschlimann for her support during the screening process.

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.

Supplemental Material: Supplemental material for this article is available online.

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• Published: 02 September 2024

Upwind moisture supply increases risk to water security

• José Posada-Marín   ORCID: orcid.org/0000-0001-7456-8772 1 , 2 , 3 ,
• Juan Salazar   ORCID: orcid.org/0000-0001-7963-7466 1 ,
• Maria Cristina Rulli   ORCID: orcid.org/0000-0002-9694-4262 4 ,
• Lan Wang-Erlandsson   ORCID: orcid.org/0000-0002-7739-5069 5 , 6 , 7 &
• Fernando Jaramillo   ORCID: orcid.org/0000-0002-6769-0136 2  

Nature Water ( 2024 ) Cite this article

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• Environmental sciences

Transboundary assessments of water security typically adopt an ‘upstream’ perspective, focusing on hazards and vulnerabilities occurring within a given hydrological basin. However, as the moisture that provides precipitation in the hydrological basin probably originates ‘upwind’, hazards and vulnerabilities potentially altering the moisture supply can be overlooked. Here we perform a global assessment of risk to water security in 379 hydrological basins accounting for upwind vulnerabilities and hazards from limited governance and environmental performance. We compare this upwind assessment with the more conventional approach focusing upstream. We find that accounting for upwind moisture supply increases the assessed risk to water security. The upwind perspective results in 32,900 km 3  yr −1 of water requirements (that is, the specific water needs of vegetation for their development) under very high risk, compared with 20,500 km 3  yr −1 under the upstream perspective. This study pinpoints the need to account for upwind moisture dependencies in global water-related risk assessments.

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Globally, around 40% of continental precipitation originates in evaporation from land 1 . This amount increases to 80–90% in some regions in Eurasia, South America and Africa 2 . Hence, precipitation over large parts of the Earth’s land surface can be vulnerable to upwind changes in the amount and timing of evaporation entering the atmosphere 3 , 4 , 5 . Land and water use related to human activities for food and energy production are known to alter such evaporation 6 , 7 , 8 , 9 , 10 . For instance, irrigation has been found to increase precipitation downwind, while deforestation decreases it 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 . Upwind loss in evaporation can result in loss in downwind precipitation with impacts on agricultural 12 , 19 , 20 , 21 , 22 and hydropower 23 , water availability in surface and groundwater resources 19 , aquatic and terrestrial ecosystems 24 , 25 , 26 and the livelihoods of many urban and rural communities 27 .

These implications have led to calls to include atmospheric water flows in transboundary water management and decision-making 28 , 29 . Other calls insist on their inclusion in international law 30 and broader water governance frameworks 28 , 31 , 32 , 33 . For instance, political instability can weaken the control of illegal practices fuelling environmental degradation, such as illicit agricultural expansion and mining 34 . The lack of land and water governance and a weak environmental performance can lead to deforestation 35 and the disappearance of ecosystems that are key for atmospheric moisture supply. As another example, a lack of voice and accountability implies a disregard for citizens in the control or curve of environmental degradation that may lead to modifications of vapour flows 36 .

Risk to water security—that is, the human capacity to ensure reliable access to safe and sufficient water resources—is typically calculated as the product of the hazard (natural or human-induced events causing harm), vulnerability (physical susceptibility to adverse effects) and exposure (elements at risk of being affected) 37 . Risk estimates usually account for upstream hazards in the hydrological basin 38 , 39 , 40 . The risks relate to downstream implications of decreasing water supply in rivers 41 , mountain glaciers 42 , lakes 43 , wetlands 44 , aquifers 45 , 46 and even soil moisture 40 . Yet, recent studies have also included the vulnerabilities and exposures arising from upwind dependencies for water security 27 , 32 . For instance, Keys et al. 27 merged upstream and upwind dependencies to estimate the integrated water supply vulnerability for 29 megacities. The growing interest in accounting for upwind dependencies for risk assessment matters as precipitation over a hydrologic basin depends on terrestrial moisture recycling (TMR), the mechanism by which upwind evaporation feeds downwind precipitation either within a hydrological basin (local moisture recycling) or across different basins. The dependency can increase or decrease the risk of natural vegetation and crops not receiving the required supply of freshwater 47 , 48 , 49 , 50 .

Here we build on previous studies that consider the upwind vulnerability of freshwater supply 27 , 32 , 33 to analyse global risks to water security. Our main aim is to quantify how accounting for upwind dependencies arising from governance and environmental performance affects the risk in 379 worldwide basins. We estimate risk from two perspectives; the first, ‘upstream’, is based on political, geographical, ecosystemic and hydroclimatic conditions in the countries sharing the hydrological basin. The second perspective, named ‘upwind’, relates to the countries sharing the hydrological basin’s precipitationshed 20 , the upwind continental regions contributing moisture. We consider the freshwater requirements of vegetation and crops within the basin as the most representative exposed asset for basin-scale water security.

We identified 379 large hydrological basins (greater than 3,400 km 2 ) covering 85 Mkm 2 whose precipitationsheds extend across more than one country. We refer to these basins as upwind transboundary basins in contrast to the typical definition of upstream transboundary (that is, the hydrological basin is shared by several countries). Around one-third of these upwind transboundary basins (153) are also upstream transboundary. From these upwind transboundary basins, the ones with the highest TMR and, thus, high upwind continental moisture dependency include the Tarim, Huang He, Amur, Yenisei and Lena River basins (Fig. 1 ). The TMR ratio can indicate how susceptible the water availability of a given hydrological basin is to changes in upwind moisture supply. For instance, a basin depending solely on moisture transport from the ocean would not be affected by any change in land use as long as atmospheric moisture convergence is not affected. Conversely, a basin depending only on continental moisture is subject to any potential change in moisture supply resulting from land use changes.

The relationship between governance ( y axis), environmental performance ( x axis), TMR ratios (colour gradient) and the area of the basin (size of the circle). Governance is calculated as the mean of the five governance indicators (voice accountability, political stability, government effectiveness, regulatory quality and the rule of law; Supplementary Fig. 2a ) reported by the World Bank 87 and area-weighted on the basis of the countries lying within the precipitationshed of each hydrological basin. Similarly, environmental performance is given by the 40 indicators of the Environmental Performance Index (Supplementary Fig. 2b ) from the Yale Center for Environmental Law and Policy 88 . The dashed red polygon highlights basins with low levels of upwind governance and environmental performance.

Source data

Most large basins typically have high TMR and low governance values (that is, less than 0.6). Interestingly, the hydrological basins with the highest TMR range between 0 and 0.6 of the maximum governance that can be obtained, pointing to low governability. The Congo River Basin is an example of a large basin with low governance and environmental performance. The water requirements of the Congo River Basin (Supplementary Fig. 1 ) have a high dependency on land cover changes occurring upwind; its TMR ratio reaches ~73%, and most of the moisture precipitating in the basin has a terrestrial origin, covering countries such as South Sudan, Central African Republic, Congo, Angola and the Democratic Republic of the Congo. Concern about the moisture dependency of the Congo River Basin arises as the low governance and environmental performance of the countries in its precipitationshed (Supplementary Fig. 2 ) may imply potential hazards to water security. Risks may arise from, for instance, threats of deforestation within the precipitationshed, which can potentially reduce upwind moisture flows, or uncontrolled irrigation, which may increase them 4 .

The first component of risk is the hazard. The potential hazard resulting after combining aspects of governance and environmental performance ( Methods and Supplementary Fig. 2 ) depends on whether these aspects are analysed for the upwind (within the precipitationshed) or upstream (within the hydrological basin) countries (Fig. 2a,b ). We can identify from both perspectives the highest hazard values in Africa, the Middle East and Asia from the combination of very low to middle values of governance and environmental performance (Fig. 2c,d and Supplementary Fig. 2 ). In African and Middle Eastern countries, the hazard is mainly related to low governance values (Supplementary Fig. 2a ), while in Asian countries, it is due to low environmental performance (Supplementary Fig. 2b ). We find that the mean global difference between assessing hazard from an upwind and upstream perspective is not statistically significant at the global scale ( P  > 0.05, Wilcoxon rank-sum test; Fig. 2b ); a similar number of basins increase or decrease their hazard. Several hydrological basins in Asia (for example, the Yangtze, Ganges and Krishna River basins) and Africa (for example, the Volta, Ogooue and Zambezi River basins) tend to increase their hazards the most when applying an upwind perspective (Fig. 2a ). In contrast, some eastern Europe basins experience the most decrease (for example, the Volga, Dniepr and Neva River basins).

a , The difference between the hazard estimates of the upwind and upstream perspectives (upwind minus upstream). b , A comparison of the distribution of hazards (box plots) of the 379 upwind transboundary basins when including countries in their hydrological basins (upstream) and their precipitationsheds (upwind). In the upstream (upwind) perspective, the minimum value recorded is 0.0 (0.0) and the maximum value is 1.0 (1.0). The centre of the box plot, representing the median of the data, is 0.31 (0.31). The bounds of the box are defined by the first quartile (Q1) and the third quartile (Q3), which are 0.03 (0.06) and 0.47 (0.58), respectively. The whiskers extend to the minimum and maximum values of the distributions. The samples were compared with a one-sided unpaired Wilcoxon rank-sum test to determine the statistical significance of the difference between both perspectives ( P value 0.25; Wilcoxon rank-sum test). c , d , The five categories (very high, high, middle, low and very low) are based on min–max normalized values of the hazard after separation in quantiles for the upstream ( c ) and upwind ( d ) perspectives.

The second risk component is the exposure of the asset at risk, that is, the total water requirements for vegetation and crops within the hydrological basin. The Amazon and Congo basins also have some of the largest total water exposure to hazards due to the large freshwater requirements of vegetation within them (Supplementary Fig. 1a ). Hence, a higher water requirements implies a larger exposure to upwind/upstream moisture supply changes. These requirements comprise both green water (GW)—the precipitation on land temporarily stored in soil and consumed by vegetation (Supplementary Fig. 1b )—and blue water (BW)—freshwater in lakes, rivers and aquifers, mainly consumed in irrigated agriculture (Supplementary Fig. 1c ). The total GW and BW requirements in the upwind transboundary basins reaches 40,600 km 3  yr −1 globally.

The third risk component, vulnerability (Fig. 3 and Supplementary Figs. 3 and 4 ), is the natural susceptibility to adverse effects. Vulnerability results are higher when considering the areas and countries within the precipitationshed than those within the hydrological basin. Contrary to the hazard, the vulnerability shows statistically significant differences between the upwind and upstream perspectives at the global scale (Wilcoxon rank-sum test, P  < 0.05; Fig. 3a,b ). Around 88% of the upwind transboundary basins increase their vulnerability when shifting from an upstream to an upwind perspective of risk (Fig. 3a ). The most marked differences occur in Europe (for example, the Danube, Volga, Dniepr and Po River basins), Asia (for example, the Tarim, Ganges, Indus and Narmada River basins) and Africa (for example, the Niger, Senegal, Ogooue and Volta River basins).

a , Geophysical vulnerability differences between perspectives (upwind minus upstream). b , The vulnerability distribution (box plots) for the 379 hydrological basins with transboundary precipitationsheds by perspective. In the upstream (upwind) perspective, the minimum value recorded is 0.0 (0.0) and the maximum value is 1.0 (1.0). The centre of the box plot, representing the median of the data, is 0.00 (0.14). The bounds of the box are defined by the first quartile (Q1) and the third quartile (Q3), which are 0.00 (0.04) and 0.05 (0.36), respectively. The whiskers extend to the minimum and maximum values of the distributions. The samples were compared with a one-sided unpaired Wilcoxon rank-sum test to determine statistical significance in differences ( P value 3.88 × 10 −55 ). c , d , Once normalized using a min–max normalization, these values are divided into five categories: very high, high, middle, low and very low, using the quantiles of their distribution for both upstream ( c ) and upwind ( d ) perspectives.

The mean global increase in vulnerability results from a mean global increase in interdependency ( P  < 0.05, Wilcox rank-sum test; Supplementary Fig. 5d ) that is more influential to the score of vulnerability than the global mean decrease in fragility ( P  < 0.05, Wilcox rank-sum test; Supplementary Fig. 5b ). Interdependency refers to the number of countries within the basin or precipitationshed, depending on the perspective, assuming that it will be easier to establish management measures and cooperation in water policy if the number of countries is low. Likewise, fragility relates to the area of the hydrological basin or precipitationshed, assuming that the capacity to meet the freshwater requirements at the scale of the hydrological basin is more fragile in smaller surface areas. Furthermore, it is worth noting that most of the basins experiencing higher vulnerabilities from an upwind perspective have relatively large TMR ratios, highlighting their dependency on continental moisture flows originating upwind. Changes in the magnitude of vulnerability between perspectives lead to a reassessment of the vulnerability categories (Fig. 3c,d ). For instance, the Amazon, Danube, Congo, Nile, Ganges and Yangtze increase their vulnerability from lower to higher levels when the upwind dependency is accounted for. Overall, the hydrological basins in Africa, the Middle East, Eastern Europe and the Indian Peninsula increase their vulnerability to very high levels.

Comparison of risk assessment frameworks

We classified the exposure in the hydrological basins (Supplementary Fig. 1a ) based on the resulting risk category for both perspectives (Fig. 4 ). We find that, while in the upstream perspective ~70% of total water requirements are under middle to very high risk, in the upwind perspective the number increases to 90% (Fig. 4a ). As such, low upwind governance and environmental performance result in 32,900 km 3  yr −1 of total water requirements (75%; purple bar) under very high risk, while an upstream lack of these aspects results in much smaller freshwater requirements under very high risk (20,500 km 3  yr −1 ; 47%). This is related to the increase in the risk category of larger basins with high freshwater requirements at the expense of reductions in the categories of smaller basins with much lower water requirements. The considerably higher upwind risk is also evidenced across both GW (Fig. 4b ) and BW (Fig. 4c ) requirements, but most notably for the latter. These results indicate an important underestimation of transboundary water security risk emerging from upwind vulnerabilities and hazards and challenge the common practice of assessing the risk to BW requirements from changes in land and water use occurring just within the hydrological basin.

a – c , The relative amount of total water ( a ), GW ( b ) and BW ( c ) requirements for each perspective and in each of the five risk categories in all hydrological basins. For example, 89% of BW requirements are at a very high risk when upwind conditions are considered.

Reassessment of global risk to water security

Notably, the upwind risk is very high in the majority of world’s largest basins (Fig. 5c ) owing to the large volumes of water requirements (exposure), which largely depend on the basin area ( R  = 0.89; Supplementary Table 1 ). Most of these large basins also exhibit high TMR dependency (Supplementary Fig. 4d ) and low values of governance and environmental performance (Fig. 1 and Supplementary Fig. 6 ). From an upwind perspective, the Congo, Nile and Niger River basins have the largest risk to water security worldwide (Supplementary Table 2 ). Interestingly, these basins also have the highest risk from an upstream perspective (Supplementary Table 2 ). Notably, the consistent high risk among both perspectives for the Congo results from the combination of (1) high dependency on terrestrial moisture from the African continent, (2) the low governance and environmental performance of the countries located in its precipitationshed and hydrological basin, (3) the high GW requirements of its tropical vegetation and (4) its large areal extent. The Volta, Zambezi and Indus River basins are also ranked in the first ten positions of risk in both perspectives.

a , Changes in risk categorization between perspectives; positive (negative) values indicate higher (lower) risk in the upwind perspective. b , The heat map shows the percentage agreement matrix, with the intersection between rows and columns indicating the percentage agreement of classified basins in each upwind (rows) and upstream (columns) risk category. For instance, about 11% of basins present a very high risk from an upwind perspective and a high risk from the upstream perspective. c , Changes in risk categorization to the 40 worldwide largest basins. The bar height indicates the risk category in the upwind perspective (see concentric circles), and its colour shows if it increases, decreases or has no changes and how many risk categories each basin changes from the upstream perspective (see colour bar in a ).

The differences in terms of risk from both perspectives result in a change in the ranking of hydrological basins (Figs. 5a and 6 ). More than half of the hydrological basins categorized with very high risk under the upstream perspective hold their risk category from an upwind perspective (Fig. 5b , 61%, top right), whereas only 38% of those in the very low risk hold their risk category (Fig. 5b , bottom left). Some of the basins with considerable changes in their risk ranking include the Amazon, Salado, Rufiji, Krishna, Yangtze and Huang He River basins, where risk increases from low (upstream) to very high (upwind) (Fig. 5a ). The Amazon and Yangtze River basins, some of the largest basins on Earth, are included in the first ten risk positions from the upwind perspective, and their vulnerability increases when the TMR dependency is accounted for. For the case of the Yangtze, its precipitationshed extends over several South Asian countries with reported low governance and environmental performance (for example, India, Myanmar and Vietnam; Supplementary Fig. 2 ). Furthermore, it ranks high in terms of exposure (water requirements of 1,000 km 3  yr −2 ) and vulnerability (that is, many countries sharing it and ~78% of TMR).

Unexpected transboundary water-related risks can emerge from the interaction of upwind vulnerabilities and hazards related to governance and environmental performance. The hazards can lead to progressive land and water use changes, potentially altering the moisture supply to downwind hydrological basins 29 , 31 , 32 , 51 , 52 . Biogeophysical properties related to vegetation on land, such as those expressed by surface albedo, surface roughness length, rooting depth, leaf stomatal conductance and leaf/stem area index, control evaporation over a given surface. Land use changes that alter vegetation can thus drive evaporation changes, with the change magnitude and direction depending on both the original vegetation cover and that resulting after the change in land use 53 , 54 , 55 , 56 . For instance, the conversion of forests to grasslands mostly reduces evaporation 54 , 56 , 57 , 58 , 59 , 60 , 61 . Forest clear-cutting has been found to reduce evaporation and increase runoff; reforestation or regrowth has resulted in the opposite effect 53 , 55 . These changes may translate into changes in the amount of moisture advected and precipitating in downwind hydrological basins 22 , 23 . Hence, the degree to which this occurs depends on the type and extent of the evaporation changes and moisture convergence.

While studies 4 , 5 , 7 , 20 , 26 , 50 , 62 , 63 already point to the corresponding heterogeneous effects of land and water use changes on moisture supply downwind, this study rather focuses on the factors of governance and environmental performance that can impede, slow, drive or foster these changes and the corresponding risks to downwind water security. As tensions related to transboundary water governance can emerge when hydrological basins are shared by different countries or regulating authorities 64 , 65 , 66 , 67 , 68 , 69 , 70 , tension among countries from sharing a specific precipitationshed could emerge as well. These tensions could increase when various countries are involved, requiring additional agreement and cooperation 68 , 69 , 70 . For instance, several basins in South America (for example, the Magdalena, Orinoco and Parana River basins) depend on moisture recycling from the Amazon Basin 7 ; their precipitationsheds extend over this basin. The Amazon Basin is shared by several countries that have tried to establish agreements to reduce deforestation but with difficult progress due to each country’s internal policies 34 , 71 . Several studies have shown the potential impacts of Amazon deforestation on precipitation and water availability in South America 7 , 11 , 18 , 23 , 50 . Accounting for upwind dependencies could then increase the interest in moisture upwind dependencies in the region, potentially leading to tensions between countries (understood not only as disputes between countries but also as any problem threatening regional water security) and cooperation to avoid or solve these tensions 72 . Similar issues could occur in other regions with a comparable context (for example, the Congo hydrological basin 73 , 74 , 75 ).

Transboundary cooperation can play a crucial role in mitigating these tensions 64 , 68 , 69 , 70 . Cooperative management and agreements on shared water resources can significantly reduce tension and promote sustainable usage 28 , 66 , 68 , 69 , 70 . Collaborative efforts in managing surface water availability, atmospheric moisture recycling and land use changes in upwind areas are relevant for maintaining water security and preventing disputes, particularly in water-scarce regions 28 , 47 , 75 , 76 . This study can help detect where and to whom cooperation strategies and efforts can be addressed to mitigate the causes of water-related tensions. Nevertheless, further research is necessary to explore the mechanisms through which cooperation can be enhanced to address these challenges effectively, particularly in the face of increased demand for water resources due to climate change and the growing globalized economy 66 .

Upwind risks are commonly overlooked in the assessment of transboundary water security. Moreover, not considering these risks may disregard the transboundary nature of numerous worldwide basins. The identified differences in this study, comparing a traditional upstream framework with an innovative upwind approach, reveal an underestimation of the risk to global water requirements. This emphasizes reassessing upwind transboundary basins according to their water risk levels. Such emerging results have and could lead to surprises in similar assessments for urban and energy-related water security 27 , 77 , 78 . We recommend that transboundary water security assessments add the upwind moisture dependency to the more common factors that threaten or affect water availability (for example, anthropogenic inter-basin water transfer and groundwater regional fluxes).

The co-dependence between upstream/downwind and downstream/upwind countries cannot be disregarded. For instance, again, in the case of tropical South America, large areas of the Andes are downwind of the Amazon forest, whereas most of the Amazon Basin is downstream of the Andes. Understanding this co-dependence could improve the hydro-cooperation between nations owing to the transnational mutual interests concerning water security and, hopefully, a more united approach to guarantee global long-term water security. This understanding depends on the confidence in tracking moisture simulations. Further research should be addressed to reduce uncertainty in these simulations through validation and intercomparison projects. Our findings, rather than a clear demonstration that the upwind moisture flux is threatened, is an alert showing worldwide basins where upwind risk could emerge with important implications to water security.

We invite a reflection on the common paradigm of managing and governing water beyond the hydrological basin and the required shift in assessing water-related risk and governance. The shift comprises a change from the view that uses only the concepts of hydrological basin or watershed—which have long been regarded as the best units and scales to govern and understand risks related to water changes 51 , 79 —to a more comprehensive view that includes atmospheric water 32 . The potential management of water beyond hydrological basin boundaries poses challenges regarding geopolitics, governance and the understanding of moisture transport. Addressing these challenges should lead to (1) the creation of new organizations or frameworks that in the future may be capable of managing water upwind or at least (2) an institutional fit of current river basin organizations to tackle the new dependencies emerging from a better understanding of moisture transport and implications for water security 80 . Assessing upwind water-related risks should improve the transboundary water agenda and help establish atmospheric governance on the water as a common good 30 , 31 .

Risk assessment frameworks

We adopted the concept of risk proposed in the Intergovernmental Panel on Climate Change Sixth Assessment Report 81 . Risk is defined as the potential consequences over a valuable subject resulting from the interaction of hazard, vulnerability and exposure. Hazard is the occurrence of natural accidents or human-induced events causing harm that may adversely affect vulnerable elements, causing loss of life, injury, damage and loss to property, infrastructure, livelihoods, service provision, ecosystems and environmental resources 81 . Vulnerability is the susceptibility, propensity or predisposition to be adversely affected. Vulnerability calculations encompass a variety of concepts and elements, including sensitivity, susceptibility and resilience, among others. These elements vary according to the system being analysed and its features 82 . Exposure is the people, livelihoods, species or ecosystems, environmental functions, services, resources, infrastructure or economic, social or cultural assets that could be adversely affected 79 . Figure 6 summarizes the mathematical formulation of the risk assessment approaches employed in this study.

a , b , Conceptual framework for risk assessment from upstream ( a ) and upwind ( b ) perspectives. The diagram illustrates the formulation of risk assessment approaches employed in this study, including the interaction of exposure ( E ), hazard ( H ) and vulnerability ( V ) within each hydrological basin and precipitationshed. The components of exposure (GW and BW requirements), hazard (governance and environmental performance) and vulnerability (sensitivity, fragility, interdependence and TMR dependency) are integrated to evaluate the potential consequences on water security.

The traditional ‘upstream’ perspective analyses hazard and geophysical vulnerability within the boundaries of the hydrological basin and its surface water supply. The ‘upwind perspective’ focuses on hazard and geophysical vulnerability across the upwind areas contributing to the basins’ moisture supply (that is, precipitationshed). Risk assessment frameworks to categorize worldwide basins according to their transboundary water security are given by equations ( 1 ) and ( 2 ):

where R is the risk, E is the exposure (that is, water requirements for vegetation and crops), H is the hazard and V is the geophysical vulnerability. The subscripts denote the perspective used (US for upstream and UW for upwind). We now describe each risk component and any particularity related to each perspective. All risk components are categorized into five groups defined using the quantiles of the distributions across the sample of 379 hydrological basins: very high, high, middle, low and very low. We also normalized the values across the sample of the 379 transboundary basins from 0 to 1 using a min–max normalization.

We frame the exposed asset of the risk assessment as the total water requirements for vegetation and crops, which are determined from the long-term annual requirements of GW and BW volumes for vegetation and crops within each hydrological basin. The exposure is the same for both upstream ( E US ) and upwind perspectives ( E UW ), relating to water requirements within the basin (equation ( 3 )).

GW is defined as the fraction of precipitation that infiltrates into the soil and is then evaporated or transpired by vegetation and crops. BW is the freshwater in surface and groundwater resource usually provided to vegetation or crops through irrigation and then evaporated or transpired. Estimations of GW and BW are obtained from a global gridded (5 arcminute) dataset of annual green and blue long-term water requirements of all land covers, natural and anthropogenic, existing within each hydrological basin during the analysis period (2008–2017). Agricultural land covers present 23 types of crop and three crop groups from the Global Spatially-Disaggregated Crop Production Statistics Data (also known as Spatial Production Allocation Mode, or SPAM) for 2010. These estimations were performed using the WATNEEDS model 83 , assessing the vertical component of the soil water balance, computing evaporation on each watershed area unit of the hydrological basin with the Penman–Monteith method 84 as modified by Allen et al. 85 . Overland flow is calculated as a soil water saturation excess mechanism and percolation is a linear function of the maximum infiltration rate and soil moisture. For a detailed description of the WATNEEDS model, we refer the reader to Chiarelli et al. 83 . Data used to calculate water requirements are reported in Table 1 .

Although the Intergovernmental Panel on Climate Change commonly uses the term hazard for climate-related physical events, trends or their physical impacts 81 , we here focus on potential human-induced hazards related to levels of governance and environmental performance. For human-induced hazards, features related to societal issues indicate the type of activity that may threaten a given system. A thorough threat assessment requires collecting information on potential threat activities within each country. Traditionally, relevant public indices have been used for this 86 . We calculated long-term hazard ( H C ) during 2008–2017 at a country scale emerging from low levels of governance ( G ) and environmental performance (EP) as (equation ( 4 ) and Supplementary Fig. 2 )

For this, we used the five World Bank’s Governance subindices for each country ( G i ) reported during 2008–2017 87 , addressing fundamental aspects of governance: (1) voice and accountability, examining the degree of civil society involvement in governmental processes, (2) political stability, focusing on the likelihood of political instability and violence, (3) government effectiveness, evaluating the government’s capacity to implement policies and provide services efficiently, (4) regulatory quality, highlighting the transparency and effectiveness of regulatory frameworks, and (5) rule of law, measuring the fair and equitable application of laws. We used the long-term average of these subindices to estimate each country’s level of governance (equation ( 5 )), where n is the number of years.

In summary, voice and accountability measure political, civil and human rights and relate to the level of participation in selecting government and the freedom of expression, association and free media 87 . A decrease in voice and accountability can, for instance, disregard the call from citizens to control or curve environmental degradation that may lead to modifications of vapour flows travelling downwind by activities such as deforestation.

Political stability measures the likelihood of violent threats to, or changes in, government, including terrorism, and can relate to the level of bellicosity of a government to generate changes that may affect the moisture supply downstream or downwind. For instance, low political instability would hamper the control of illegal practices fuelling environmental degradation, such as illicit agricultural expansion and mining.

Government effectiveness visualizes the competence of the bureaucracy and the quality of public service delivery, and a low value would imply a limited capacity of the government to control environmental degradation per se. Regulatory quality measures the incidence of policies that are unfriendly to markets. It also refers to a country’s internationalization level and immersion in the international agenda by international commitments and regulations.

Regulatory quality would directly target the issues related to shared political institutions (such as international political and legal arrangements). It also represents the complexity of political frameworks considering different levels of organization (scales), for example, multiple countries (for example, the European Union), or inside countries (there are also problems inside countries, for example, among states sharing the Colorado River in the USA). Hence, a low regulatory quality will imply a higher water security hazard.

Rule of law shows the measuring perceptions of the extent to which agents have confidence in and abide by the rules of society, mostly concerning the quality of contract enforcement, the police and the courts and the likelihood of crime and violence. A low score of rule and law increases the hazard of water security. Finally, the control of corruption, which measures corruption and state capture, also relates to the potential of controlling and avoiding environmental degradation. A low score also implies a higher hazard of water security.

These subindices are combined to offer a holistic view of governance in each country, enabling meaningful comparisons on a global scale. Furthermore, we used the 40 subindices of the Environmental Performance Index by the Yale Center for Environmental Law and Policy 88 . This comprehensive measure of the countries’ environmental management evaluates environmental health and ecosystem vitality across different nations. The index considers indicators such as water resources management, biodiversity conservation and climate change mitigation efforts. Some of these subindices are pertinent for the upstream and upwind risks to water security, as they relate directly to land use changes that may potentially affect downwind moisture supply. These include tree cover loss, grassland loss, wetland loss and terrestrial biome protection. By analysing these factors, the index provides insights into a country’s environmental policies, their effectiveness and areas for improvement. This index is valuable for policymakers and researchers to assess progress and prioritize actions towards sustainable development and environmental protection globally. We know that several subindices of the environmental performance metric are not related to water and land cover environmental characteristics. However, we prefer to use the full metric as a holistic proxy of environmental performance relevant to water security rather than arbitrarily selecting and dropping specific subindices. Thus, we calculated the environmental performance as the long-term average of these 40 subindices (EP i ) (equation ( 6 )), where n is the number of years.

Upstream hazard was calculated for each hydrological basin as an area-weighted average for all countries within the hydrological basin ( H US ; equation ( 7 )). Upwind hazard ( H UW ) was calculated similarly but using the precipitationshed area instead of the hydrological basin area (equation ( 8 )). The n is the number of countries sharing the basin or precipitationshed.

Here A ws and A ps represent the areas for each ( i ) of the total countries ( n ) falling in the hydrological basin and precipitationshed, respectively.

Geophysical vulnerability

Vulnerability is a physical feature used for quantifying risk 76 . This study calculated geophysical vulnerability ( V ) as a function of different physical variables, which sometimes differed between both perspectives. From an upstream perspective (equation ( 9 )), vulnerability is a function of hydrological basin features: sensitivity ( S ), fragility ( F ) and interdependency ( I ). From an upwind perspective (equation ( 10 )), we added one more variable related to TMR dependency ( D ). Fragility and interdependency were adjusted to the spatial extent of the precipitationshed to represent the physical links established by upwind moisture dependency. Again, subscripts denote the perspective used (US, upstream; UW, upwind).

Sensitivity

Sensitivity is calculated from a min–max normalized water scarcity index estimated as precipitation ( P ) minus actual evaporation (EV) plus inter-basin surface transfers (man-made, T ). Precipitation and actual evaporation are based on data from ERA5 from 2008 to 2017, which estimate the long-term mean of surface water balance (SWB) 89 . For inter-basin surface transfers, we have gathered data on transfers from several references, most importantly from Dynesius and Nilsson 90 , who document inter-basin transfers in 139 hydrological basins worldwide. They report the amount of freshwater transferred as a percentage of the runoff before any manipulation. The data even specify if the effect of the inter-basin transfer is negative or positive. Hence, we adjust the values of P   –  EV originally obtained from ERA5 data with this estimate accordingly. For other basins not included in the work of Dynesius and Nilsson 90 , we have also relied on different sources mentioned in the global assessment of Nilsson et al. 91 and other sources such as Dobbs et al. 92 and Gupta and van der Zaag 93 . Note that the data on inter-basin transfers may not agree with the ERA5 data, yet we have to assume that the amount of water transferred is constant in time and that some inter-basin transfers may not be reported in these databases.

We used the same sensitivity estimate for both perspectives (equation ( 11 )). To homogenize the values across the sample of the 379 transboundary basins, all N values were normalized from 0 to 1 (equations ( 12 ) and ( 13 )) using the maximum (SWB MAX ) and minimum (SWB MIN ) values of the sample. We inverted the value so that higher values represent more sensitivity to upwind or upstream changes in water availability due to less water running on the hydrological basin’s surface, which agrees with higher risk corresponding to higher sensitivity. We assume that the water requirements are less vulnerable to governance and environmental performance changes when more water is available in the hydrological basin.

From the upstream perspective (equation ( 14 )), fragility relates to the inverse of the area of the hydrological basin ( A ws ), while from an upwind standpoint (equation ( 15 )), it relates to that of the precipitationshed ( A ps ) (Supplementary Fig. 5 ). To homogenize the values across the sample of the 379 transboundary basins, all values were normalized from 0 to 1. From the first perspective, we assume that the socioecological system and capacity to meet the freshwater requirements within the hydrological basin is more fragile to changes in governance and environmental performance in smaller hydrological basins than in large basins. For instance, in a larger basin, it is most likely that, while some freshwater requirements are affected in some parts of the hydrological basin, other parts will not experience such affectation. On the contrary, in a small hydrological basin, all freshwater requirements will most possibly be affected similarly 52 , 94 . In the upwind perspective, a similar logic is proposed: the freshwater requirements in a hydrological basin will be less affected when the basin has a large precipitationshed, as the particular hazard in an upwind country may not be as representative when other countries and land areas are involved.

Interdependency

From the upstream perspective (equation ( 16 )), interdependency is estimated from the number of countries within a basin (NC ws ). From the upwind perspective (equation ( 17 )), this variable depends on the countries sharing the precipitationshed (NC ps ). For both perspectives, high values represent a high interdependency with cooperation concerning water resources more difficult between several countries 95 . The assumption is that it will be easier to establish management measures and cooperation if the number of countries is lower. We must state that the level of cooperation in water governance does not strictly depend on the number of countries but also on other factors related to governance, which, for this particular assessment, we include as part of the hazard (see ‘Hazard’ section). To homogenize the values across the sample of the 379 transboundary basins, all values were normalized from 0 to 1.

TMR dependency

The TMR dependency in the upwind perspective (Duw; equation ( 18 )) relates to the contribution of continental evaporation to precipitration in the hydrological basin (Pc). The higher the value, the higher the dependency on TMR.

Finally, we explored collinearity between all variables involved in the risk assessment. As a summary, we found that the variables involved in calculating risk show low collinearity in both perspectives (Supplementary Tables 3 and 4 ), indicating that risk results from nonlinear interactions between its components. Upstream interdependency (that is, the number of countries upstream) correlates highly with upstream risk (Supplementary Table 1 ). From the upwind perspective, we found a high correlation between interdependency and vulnerability (Supplementary Table 5 ).

Characterizing TMR ratio in worldwide basins

We used the vectorized polygon dataset from the Major River Basins of the World project of the Global Runoff Data Centre to extract the large hydrological basins used in our risk assessments 96 . This dataset incorporates data from the HydroSHEDS database 97 and provides the boundaries of 405 river basins. A total of 26 of these basins are not transboundary from the viewpoint of neither the upwind nor the upstream perspectives.

We quantified the TMR ratio in all basins on the basis of the tracking simulation performed by Tuinenburg et al. 74 using the UTrack model 98 at 1.0° resolution (available at https://doi.pangaea.de/10.1594/PANGAEA.912710 ). This simulation spans from 2008 to 2017 and presents monthly climatological means for recycling. Correspondingly, we use this period as the reference for our risk assessments. The UTrack is a Lagrangian moisture tracking numerical algorithm used to study worldwide atmospheric moisture transport processes 99 , 100 , 101 , 102 , 103 . The model tracks parcels of moisture through the atmosphere from their evaporation sources to precipitation sinks. First, evaporated moisture from the land surface is released into atmospheric parcels. Next, atmospheric trajectories for each parcel are calculated, and finally, the moisture contribution to precipitation in each grid cell for each parcel is allocated. For a further detailed description of the UTrack, refer to Tuinenburg and Staal 98 . Calculations of TMR ratio (that is, precipitation fraction with terrestrial origin) used data of precipitation, precipitable water, evaporation, wind speed and direction obtained from the ERA5 reanalysis on a 0.25° global grid.

To obtain the TMR ratio of a hydrological basin, we took all evaporation contribution fractions from the continental sources towards each basin and multiplied them with evaporation to estimate the moisture flow. Finally, we summed these fluxes and divided them by the total precipitation over the basin. Finally, for validation and assessing uncertainty, we compared for specific hydrological basins the TMR dependency results obtained with UTrack with those obtained with simulations using the Eulerian WAM2-Layers model 104 (see Supplementary Fig. 7 and the ‘Uncertainty analysis’ section).

Structuring the transboundary precipitationshed

Keys et al. 20 define a precipitationshed as the upwind surface areas providing evaporation as a contribution to precipitation in a determined location. The precipitationshed is then calculated using polygons to delimit regions according to contribution levels. Previous studies have suggested and discussed different thresholds to delimit a precipitationshed boundary of continental recycled precipitation (for example, 70% (ref. 20 ) and 40% (ref. 50 )). We here used a higher value (80%) based on (1) an uncertainty exploration (Supplementary Fig. 7b,c ), (2) the moisture tracking state of the art (it is higher than the minimum required to delineate our precipitationsheds 50 ) and (3) the need for high representativeness of continental sources.

We used the UTrack dataset to delimit the transboundary precipitationshed for each hydrological basin. First, we took evaporation contribution fluxes from the continental sources towards each basin; next, we divided these values by each basin’s total precipitation to obtain the continental precipitation recycling ratio per pixel. Finally, we used these values to delimit the regions according to contribution levels. Following Weng et al. 50 , we used the terrestrial component of precipitationsheds in our calculations because land surface alterations in each country could directly impact the TMR. The estimation of TMR and precipitationshed extent from the UTrack dataset is justified by the lower computational costs compared with those when performing a tracking simulation. Furthermore, the UTrack simulation that generates this dataset uses the ERA5 data with a 0.25° high-resolution climatological dataset. We explored the uncertainty in our estimates of precipitationsheds’ extensions by comparing those from the ten largest worldwide basins using WAM2-Layers (Supplementary Fig. 7b,c ).

Uncertainty analysis

We studied uncertainty in our results related to the hazard and the physical links introduced by upwind dependencies. First, we analysed the sensitivity of the results regarding the risk arising from different governance and environmental performance values by using twice the standard deviations of all their subindices during 2008–2017, generating a range of possible results (Supplementary Fig. 8 ).

Furthermore, uncertainty from tracking moisture simulations arises because these models use a simplified representation of the real-world and climatological data. To explore these uncertainties, we compared the estimated TMR dependency and precipitationshed from the UTrack dataset with simulations using WAM2-Layers in the ten largest basins worldwide. These models present different physical approaches (Lagrangian versus Eulerian) and climatological inputs (ERA5 versus ERA-Interim, with 0.25° and 1.5° of spatial resolution, respectively). This comparison was constrained to a few hydrological basins owing to the high computational costs of using WAM2-Layers to estimate the extension of precipitationsheds. Unfortunately, the previous tracking simulation dataset using this model 104 does not allow us to estimate the extension of the precipitationshed. For further details on the uncertainty analysis, see Supplementary Information .

Data availability

Data results are available via Zenodo at https://doi.org/10.5281/zenodo.11474249 (ref. 105 ) with CCA 4.0 licence.

Code availability

Code used to delimit continental precipitationsheds from UTrack dataset is available via GitHub at https://github.com/josepomarin/PshedUTrack.git .

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Acknowledgements

This work was funded by the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) Project 2022-02148, the Swedish Research Council (VR) Project 2021-05774. J.P.-M. was funded by the Colombian Ministry of Science, Technology and Innovation (Minciencias) through the programme ‘Excelencia doctoral del Bicentenario’ Grant 20230017-25-2020. J.S. was funded by the Colombian Ministry of Science, Technology, and Innovation (Minciencias) through the SOS-Cuenca research programme ‘SOStenibilidad de sistemas ecológicos y sociales en la CUENCA Magdalena-Cauca bajo escenarios de cambio climático y pérdida de bosques’ (grant no. 1115-852-70719). L.W.-E. was supported by funding from FORMAS (2019-01220, 2022-02089, 2023-0310 and 2023-00321), Horizon Europe (101081661), the IKEA Foundation, the Marianne and Marcus Wallenberg Foundation and the Marcus and Amalia Wallenberg Foundation. The funders had no role in the design, data collection and analysis, decision to publish or preparation of the paper.

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José Posada-Marín & Juan Salazar

Department of Physical Geography/Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden

José Posada-Marín & Fernando Jaramillo

Grupo de Investigación en Innovación Digital y Desarrollo Social, IU Digital de Antioquia, Medellín, Colombia

José Posada-Marín

Department of Civil and Environmental Engineering, Politecnico di Milano, Milan, Italy

Maria Cristina Rulli

Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden

Lan Wang-Erlandsson

Anthropocene Laboratory, the Royal Swedish Academy of Sciences, Stockholm, Sweden

Potsdam Institute for Climate Impact Research, Member of the Leibnitz Association, Potsdam, Germany

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Contributions

Design: J.P.-M., J.S. and F.J. Project administration and supervision: F.J. Methodology: J.P.-M., J.S. and F.J. Deployment and sampling: J.P.-M. Formal analysis: J.P.-M., J.S., M.C.R., L.W.-E. and F.J. Writing—original draft: J.P.-M., J.S. and F.J. Writing—review and editing: J.P.-M., J.S., M.C.R., L.W.-E. and F.J. Modelling: J.P.-M. and M.C.R. All authors contributed to discussion of the results and the paper.

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Supplementary Figs. 1–8 and Tables 1–5.

Source Data Fig. 1

Environmental Performance Index, governance, TMR ratio and area for each of the 379 analysed basins.

Source Data Fig. 2

Hazard from upstream and upwind perspectives, and their differences for each of the 379 analysed basins.

Source Data Fig. 3

Vulnerability from upstream and upwind perspectives, and their differences for each of the 379 analysed basins.

Source Data Fig. 4

Relative amount of total water, GW and BW requirements for each perspective and in each of the five risk categories in each of the 379 analysed basins.

Source Data Fig. 5

Risk category from upstream and upwind perspectives, their changes and area for each of the 379 analysed basins.

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Posada-Marín, J., Salazar, J., Rulli, M.C. et al. Upwind moisture supply increases risk to water security. Nat Water (2024). https://doi.org/10.1038/s44221-024-00291-w

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A novel approach for plunging using plungers of predefined geometry

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• Published: 01 September 2024

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• Mohammad A. Omari   ORCID: orcid.org/0000-0001-9501-7531 1 ,
• Mahmoud M. Rababah 2 &
• Ma’mon M. AlFakeh 1  

Plunge milling is a very efficient roughing process. Optimizing the tool path of the plungers will enhance the plunge process. A novel approach is developed and introduced in this paper to optimize the tool path of the plungers using plungers of predefined geometry. For this purpose, maximizing the covered plunging area and minimizing the number of the plunging cycles are required. Unlike the current methods that demand specific geometry for the plungers, the proposed approach starts from predefined geometry for these plungers according to the availability in the market; eliminating the constrains imposed by the current methods. The developed approach combines two basic approaches, namely: The medial axis transformation approach and the offset techniques approach in order to generate data points within the contour of the required shape. Data points are then studied for possible selection to ensure an optimal plunging process. The developed approach is validated by simulation and compared with previous work, its superiority over the current methods is confirmed through many case studies. For instance, a flower shape with a multi-regions contour and the human hand shape with some narrow and complicated regions. The studied case studies revealed the possibility of reducing the number of plungers used and increasing the plunging area. The effectiveness of the approach for narrow shapes and its orientation-independence is obvious in comparison with the current methods; qualitatively through figures and quantitatively by reduce the number of plungers to 37 instead of 72, and the plunging ration is improved to 92.3, surpassing the previous method’s ratio of 72.26 as shown in Table 2. The last comparison includes a complex pocket with island, our findings indicate an improvement over the previous method in two key aspects: reducing the number of tools and expanding the covered area.

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Department of Mechanical Engineering, Jordan University of Science and Technology, P.O. Box 3030, Irbid, 22110, Jordan

Mohammad A. Omari & Ma’mon M. AlFakeh

Department of Mechanical Engineering, the Hashemite University, Zarqa, 13133, Jordan

Mahmoud M. Rababah

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Omari, M.A., Rababah, M.M. & AlFakeh, M.M. A novel approach for plunging using plungers of predefined geometry. Int J Interact Des Manuf (2024). https://doi.org/10.1007/s12008-024-02079-4

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Received : 19 September 2023

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Published : 01 September 2024

DOI : https://doi.org/10.1007/s12008-024-02079-4

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