Case Study Research and Applications Design and Methoda by Campbell

research. To cater to the latter audience, Sage Publications has made a companion website, study.sagepub.com/yin6e, available to post supplementary materials. The website therefore contains the materials that might be more helpful and informative for scholars already advanced in their knowledge of case study research. Hopefully, such an arrangement will permit readers to make their own forays into case study research, and on their own terms. For instance, the fifth edition had contained several tutorials that explored some key issues, with authoritative references, in greater depth. This material, along with a lot of other reprints and writings that preceded even the first edition of this book, is now found on the website. The hope is that the website can help anyone who might want to know more but not to interfere with those of you just setting out on your initial journey with case study research. One place where the sixth edition remains steadfastly consistent with all the earlier editions deserves repeated mention: Donald Campbell’s insightful foreword. His succinct words, written more than 30 years ago, still stand as a masterpiece about social science methods. Within the context of today’s research dialogues, Campbell’s work continues, remarkably, to speak with freshness and direct relevance. His foreword also positions well the role of case study research as portrayed in this book. I continue to be deeply honored by the inclusion of this foreword and have attempted to return but a modest contribution, now to his memory, in a subsequent publication (Yin, 2000b). The successful practicing of this edition’s techniques and guidance means that case study research will be better than in the past. The ultimate goal, as always, is to improve our social science methods and practices over those of previous cohorts of scholars. Only in this manner can every cohort make its own mark, much less establish its own competitive niche. As a final note, I conclude this preface by repeating a portion from the preface to the fourth edition. In it, I suggested that anyone’s ideas about case study research —and about modes of social science inquiry more generally—must have deeper roots. Mine go back to the two disciplines in which I was trained: history as an undergraduate and brain and cognitive sciences as a graduate. History and historiography first raised my consciousness regarding the importance (and challenge) of methodology in the social sciences. The unique brand of basic research in brain and cognitive science that I learned at MIT then taught me that empirical research advances only when accompanied by theory and logical inquiry, and not when only treated as a mechanistic data collection endeavor. This lesson turns out to be a basic theme in doing case study research. I have therefore dedicated this book to the person at MIT, Prof. Hans-Lukas Teuber,

who taught me this best and under whom I completed a dissertation on face recognition, though he might only barely recognize the resemblances between past and present were he alive today. Notes 1. The counts are based on the appearance of a given word or term in published books. Unfortunately, Ngram Viewer does not indicate the number of books covered during any particular period of time, so the website does not provide the number of books accessed from 1980 to 2008. Overall, Ngram Viewer claims that it has amassed about 4% of all books ever published (Michel et al., 2010). 2.1 chose not to select a fifth term, “qualitative research,” because its usage overlaps in some unknown way with “case study research.” The inclusion would have clouded my main intended comparison, which was between “case study research” and the other three types of inquiries. 3. Avid supporters of the gold standard have nevertheless published a research article using “case study” in its title (Cook & Foray, 2007). Readers should not take this as an example of how to do case study research, however. The article mainly contains the authors’ rendition of a set of events at the outset of the decade in question (a set that apparently could not be told with quantitative methods) but does not present much actual evidence to support that rendition. (The rendition may be insightful, but whether it should be accepted as an example of case study research or as a “popular” case study remains an open question.) 4. The Internet source of this tally does not indicate the time period that it covered, but Google Scholar started in 2004 and the source for the tally appeared in 2016, so an estimate of 2004 to 2015 as the years that were covered would be one guess. 5. An interesting side note would point to developments in one of the other social science methods—surveys. In contemporary political polls, note that the “margin of error” is now reported in the popular media every time a polling result is cited. Such reporting did not usually occur in the past. One offshoot of the reference to the margin of error is that it readily reminds (and educates) the audience that these data were based on surveys that respectfully followed relevant research procedures. What might be helpful in the (distant) future is for the popular case studies to contain an analogous reminder, if the case study indeed used any research procedures, such as triangulating data from two or more sources of evidence.

participated in these sessions, which have been held annually for several years. Serendipitously, the students’ questions often produce nuggets of wisdom, and I thank the students for these nuggets and Nancy and Kim for initiating the entire arrangement. In yet another field, a research team led by Katherine Patterson Kelly (PhD, RN, Nurse Scientist) at the Department of Nursing Research and Quality Outcomes, Children’s National Health System, has been studying therapy groups in a series of case studies. Collecting and analyzing data from each group as a whole (as well as from the group’s members individually) has led Kelly and her team into an innovative realm. I again have been fortunate to participate in this work and thank Kelly and Pamela S. Hinds (PhD, RN, FAAN, and Professor of Pediatrics, The George Washington University), the director of the department, for sharing this research experience. As part of the preparation of this sixth edition, Sage Publications invited reviewers to reflect upon their experiences in using the fifth edition. I thank them for their extensive and helpful comments, and I hope that they will see the adoption of at least some of their suggestions: Michael A. Guerra, Lincoln University Landon E. Hancock, Kent State University Ellen S. Hoffman, University of Hawai’i at Manoa Barbara J. Holtzclaw, The University of Oklahoma Health Sciences Center, Fran and Earl Ziegler College of Nursing Claretha Hughes, University of Arkansas Kriss Y. Kemp-Graham, Texas A&M University—Commerce Joseph McNabb, Professor of the Practice Eva Mika, Northcentral University David M. Sprick, Park University Bruce E. Winston, Regent University, School of Business & Leadership Asta Zelenkauskaite, Drexel University Finally, the editors at Sage played an important role in reshaping this sixth edition so that it would include the applications. Vicki Knight started the process before retiring from Sage, and Leah Fargotstein carried the project forward thereafter. To them I owe a debt of gratitude as well as to several others at Sage who contributed to the production and sharpening process—Kelly DeRosa, Gillian Dickens, and Yvonne McDuffee. Nonetheless, as with the earlier versions of this book, I alone bear the responsibility for this sixth edition.

About the Author Robert K. Yin is President of COSMOS Corporation, an applied research and social science firm. Over the years, COSMOS has successfully completed hundreds of projects for federal agencies, state and local agencies, and private foundations. Outside of COSMOS, Dr. Yin has assisted numerous other research groups, helping to train their field teams or to design research studies. The most recent such engagements have been with The World Bank, the Division of Special Education and disAbility Research at George Mason University, the Department of Nursing Research and Quality Outcomes at the Children’s National Health System (Washington, D.C.), and the School of Education, Southern New Hampshire University. Dr. Yin has authored more than 100 publications, including authoring or editing 11 books (not counting the multiple editions of any given book). Earlier editions of the present book have been translated into eight languages (Chinese, Japanese, Korean, Swedish, Romanian, Italian, Polish, and Portuguese), and a second book on Qualitative Research From Start to Finish (2016) is in its second edition and has been translated into four languages (Chinese, Korean, Swedish, and Portuguese). Dr. Yin received his BA in history from Harvard College (magna cum laude) and his PhD in brain and cognitive sciences from MIT. Doing Case Study Research: A Linear but Iterative Process

Chapter 1: Plan o Identify the relevant situation for doing a case study, compared with other research methods e Understand the twofold definition of a case study inquiry o Address the traditional concerns over case study research e Decide whether to do a case study Abstract You want to study something relevant but also exciting—and you want to use an acceptable if not esteemed social science method. Doing a “case study” strikes your fancy, but how you might do a good one remains a challenge, compared with doing an experiment, survey, history, or archival analysis (as in economic or statistical modeling). You are intrigued and want to learn more about doing a case study. This chapter suggests that you might favor choosing case study research, compared with the others, when (1) your main research questions are “how” or “why” questions, (2) you have little or no control over behavioral events, and (3) your focus of study is a contemporary (as opposed to entirely historical) phenomenon—a “case.” The chapter then offers a common definition to be applied to the ensuing case study. Among the variations in case studies, yours can include single or multiple cases, can even be limited to quantitative evidence if desired, and can be part of a mixed-methods study. Properly doing a case study means addressing five traditional concerns—conducting the research rigorously, avoiding confusion with nonresearch case studies (i.e., popular case studies, teaching- practice case studies, and case records), arriving at generalized conclusions if desired, carefully managing your level of effort, and understanding the comparative advantage of case study research. The overall challenge makes case study research “hard,” although it has classically been considered a “soft” form of research. Being Ready For The Challenge, And Setting High Expectations Doing case study research remains one of the most challenging of all social science endeavors. This book will help you—whether an experienced or

emerging social scientist—to deal with the challenge. Your goal is to design good case studies and to collect, present, and analyze data fairly. A further goal is to bring your case study to closure by composing a compelling article, report, book, or oral presentation. Do not underestimate the extent of the challenge. Although you may be ready to design and do case study research, others may espouse and advocate other modes of social science inquiry. Similarly, prevailing federal or other research funds may favor methods other than case studies. As a result, you may need to have ready responses to some inevitable questions and set high expectations for yourself. Following a clear methodological path. First and foremost, you should explain how you are devoting yourself to following a clear methodological path. For instance, a conventional starting place would be to review literature and define your case study’s research questions. Alternatively, however, you might want to start with some fieldwork first, prior to defining any theoretical concerns or even examining the relevant research literature. In this latter mode, you might be entertaining a contrary perspective: that what might be “relevant,” as well as the pertinent research questions, may not be determinable ahead of knowing something about what’s going on in the field. Regardless of your starting place, the path should explicitly show how you will adhere to formal and explicit procedures when doing your research. Tip: How do I know if I should be doing case study research? 4 P4 There’s no formula, but your choice depends in large part on your research question(s). The more that your questions seek to explain some contemporary circumstance (e.g., “how” or “why” some social phenomenon works), the more that case study research will be relevant. Case studies also are relevant the more that your questions require an extensive and “in-depth” description of some social phenomenon. ‘What are some other reasons you might cite for doing or not doing case study research? Along these lines, this book offers much guidance. It shows how case study research is distinctive but also covers procedures central to all modes of social science research. In shaping your case study, you might like to know whether to

work(s) in your chosen field may point to some subtle ways of customizing your case study in relation to that field. For instance, Appendix A describes the case study’s lengthy but peculiar history in one of the disciplines—psychology. Whatever your field of interest, the distinctive need for case studies arises out of the desire to understand complex social phenomena. Case studies allow you to focus in-depth on a “case” and to retain a holistic and real-world perspective— such as in studying individual life cycles, small group behavior, organizational and managerial processes, neighborhood change, school performance, international relations, and the maturation of industries. Comparing Case Studies With Other Social Science Research Methods When and why would you want to use a case study to examine some social science topic? Should you consider doing an experiment instead? A survey? A history? An analysis of archival records, such as the statistical modeling of epidemiological trends or of student performance in schools? These and other choices represent different research methods. Each is a different way of collecting and analyzing empirical evidence. Each follows its own logic and procedures. And each method has its own advantages and disadvantages. To get the most out of doing case study research, you may need to appreciate these distinctions. Figure 1.1 Sampler of Works Devoted to Case Study Research in Specific Fields

ACADEMIC DISCIPLINES: Anthropology and Ethnography | Burawoy, 1991 Political Science George & Bennett, 2005; Cerring, 2004 Psycholinguistics Duff, 2008 Psychology Bromley, 1986; Campbell, 1975; McLeod, 2010 Sociology Feagin, Orum, & Sjoberg, 1991; Hamel, 1992; Mitchell, 1983; Platt, 1992 PRACTICING PROFESSIONS: Accounting Bruns, 1989 Business and Intemational Dul & Hak, 2008; Farquhar, 2012; Gibbert, Ruigrok, & Business Wicki, 2008; Johnston, Leach, & Liu, 2000; Meyer, 2001; Piekkari, Welch, & Paavilainen, 2009; Vissak, 2010 Education Hamilton & Corbett-Whittier, 2013; Yin, 2006a Evaluation U.S. Government Accountability Office, 1990 Health Care Carolan, Forbat, & Smith, 2015; Walshe, 2011 Marketing Beverland & Lindgreen, 2010 Nursing Baxter & Jack, 2008; De Chesnay, 2017 Public Administration Agranoff & Radin, 1991 Social Work Gilgun, 1994; Lee, Mishna, & Brennenstuhl, 2010 Software Engineering Runeson, Host, Rainer, & Regnell, 2012 Relationships Among the Methods: Not Hierarchical A common misconception is that the various research methods should be arrayed hierarchically. Many social scientists still implicitly believe that case studies are only appropriate for the exploratory phase of an investigation, that surveys and histories are appropriate for the descriptive phase, and that experiments are the only way of pursuing explanatory or causal inquiries. The hierarchical view reinforces the idea that case study research is only a preliminary mode of inquiry and cannot be used to describe phenomena or test propositions. However, you need not automatically accept this hierarchical view. You would point to the fact that experiments with an exploratory motive have certainly always existed. In addition, the development of causal explanations has long been a serious concern of historians, especially reflected by the subfield known as historiography.

2A. A Neighborhood Scene Street Corner Society (1943/1993), by William F. Whyte, has for decades been recommended reading in community sociology. The book is a classic example of a descriptive case study. It traces the sequence of interpersonal events over time, describes a subculture that had rarely been the topic of previous study, and discovers key phenomena—such as the career advancement of lower income youths and their ability (or inability) to break neighborhood ties. The study has been highly regarded despite its taking place in a small urban neighborhood (under the pseudonym of “Cornerville”) and during a time period now nearly 100 years ago. The value of the book is, paradoxically, its generalizability even to contemporary issues of individual performance, group structure, and the social structure of neighborhoods. Later investigators have repeatedly found remnants of Cornerville in their work, even though they have studied different neighborhoods and different time periods (also see BOX 21, Chapter 4). 2B. A National Crisis Neustadt and Fineberg’s excellent analysis of a mass immunization campaign was issued originally as a government report in 1978, The Swine Flu Affair: Decision-Making on a Slippery Disease, and later published independently as The Epidemic That Never Was (1983). The case study describes the immunization of 40 million Americans that took place under President Gerald Ford’s administration, when the United States was faced with a threat of epidemic proportions from a new and potentially lethal influenza strain. Because the case study has become known as an exceptionally well-researched case study, contemporary policy makers have continued to consult it for any generalizable lessons for understanding the quandaries of health crises and public actions in light of new threats by flu epidemics, such as the HIN1 strain of 2008-2010 and by viruses such as the Ebola and Zika outbreaks of 2013 to the present. The more appropriate view may be an inclusive and pluralistic one: Every research method can be used for all three purposes—exploratory, descriptive, and explanatory studies. There may be exploratory case studies, descriptive case studies, or explanatory case studies. Similarly, there may be exploratory experiments, descriptive experiments, and explanatory experiments. What distinguishes the different methods is not a hierarchy but the three

important conditions discussed next. As an important caution, however, the clarification does not imply that the boundaries between the modes—or the occasions when each is to be used—are always sharp. Even though each mode of inquiry has its distinct characteristics, there are large overlaps among them. The goal is to avoid gross misfits—that is, when you are planning to use one mode of inquiry but another is really more advantageous. Exercise 1.1 Defining Different Types of Research Case Studies B] Define the three types of case studies used for research purposes: (a) explanatory case studies, (b) descriptive case studies, and (c) exploratory case studies. Compare the situations in which these different types of case studies would be most applicable. Now name a case study that you would like to conduct. Would it be explanatory, descriptive, or exploratory? Why? When to Use the Different Methods The three conditions consist of (a) the form of research question posed, (b) the control a researcher has over actual behavioral events, and (c) the degree of focus on contemporary as opposed to entirely historical events. Figure 1.2 displays these three conditions and shows how each is related to five social science research methods: experiments, surveys, archival analyses (e.g., economic modeling, or a statistical analysis in an epidemiological study), histories, and case studies. The importance of each condition, in distinguishing among the five methods, is as follows. Figure 1.2 Relevant Situations for Different Research Methods Experiment how, why? yes yes Survey who, what, where, how | no yes many, how much? Archival Analysis who, what, where, how | no yes/no many, how much? History how, why? no no Case Study how, why? no yes Source: COSMOS Corporation.

Bradshaw, 1999, also presented in Application 8, Chapter 5 of this book)—you would be less likely to rely on a survey or an examination of archival records and might be better off doing a history or a case study. Similarly, if you wanted to know how research investigators may possibly (but unknowingly) bias their research, you could design and conduct a series of experiments (see Rosenthal, 1966). Let us take two more examples. If you were studying “who” had suffered as a result of terrorist acts and “how much” damage had been done, you might survey residents, examine government records (an archival analysis), or conduct a “windshield survey” of the affected area. In contrast, if you wanted to know “why” the act had occurred, you would have to draw upon a wider array of documentary information, in addition to conducting interviews, and you would likely be doing a case study. Moreover, if you focused on the “why” question in more than one terrorist act, you would probably be doing a multiple-case study. Similarly, if you wanted to know “what” the outcomes associated with a new governmental program had been, you could answer this question by doing a survey or by examining economic data, depending on the type of program involved. Questions—such as “How many clients did the program serve?” “What kinds of benefits were received?” “How often were different benefits produced?”—all could be answered without doing a case study. But if you needed to know “how” or “why” the program had worked (or not), you would lean toward a case study or a field experiment. To summarize, the first and most important condition for differentiating among the five social science research methods is to classify the form of the research question being asked. In general, “what” questions may be either exploratory (in which case, any of the methods could be used) or about prevalence (in which surveys or the analysis of archival records would be favored). “How” and “why” questions are likely to favor using a case study, experiment, or history. Exercise 1.2 Defining a Case Study Research Question 3 Develop a “how” or “why” question that would be the rationale for a case study that you might conduct. Instead of doing a case study, now imagine that you only could do a history, a survey, or an experiment (but not a case study) to address this question. What would be the distinctive advantage of doing a case study, compared with these other methods, in order to address

the question? Defining your research question(s) is probably the most important step to be taken in a research study, so you should be patient and allow sufficient time for this task. The key is to understand that your research questions have both substance—for example, What is my study about?—and form—for example, am I asking a “who,” “what,” “where,” “how,” or “why” question? Other scholars have focused on some of the substantively important issues (see Campbell, Daft, & Hulin, 1982). The point of the preceding discussion is that the form of the question can provide an important clue regarding the appropriate research method to be used. Remember, too, that the methods can overlap. Thus, for some questions, a choice among methods might actually exist. Be aware, finally, that you (or your academic department) may be predisposed to favor a particular method regardless of the study question. If so, be sure to create the form of the study question best matching the method you were predisposed to favor in the first place. Exercise 1.3 Identifying the Research Questions When Other Research Methods Are Used 3 Locate a research study based solely on the use of a survey, history, or experiment (but not a case study). Identify the research question(s) addressed by the study. Does the type of question differ from those that might have appeared as part of a case study on the same topic, and if so, how? (b) Control over behavioral events (see Figure 1.2, column b)— and focus on contemporary as opposed to entirely historical events (see Figure 1.2, column c). Assuming that “how” and “why” questions are to be the focus of study, these two remaining conditions help to distinguish further among a history, a research case study, and an experiment. A history has virtually no such control and deals with the “dead” past—that is, when direct observations of the event(s) being studied are not possible and when no relevant persons are alive to report, even retrospectively, what occurred. The historian must then rely on primary documents, secondary documents, and cultural and physical artifacts as the main sources of evidence. A more contemporary version of historical research can study the recent but not quite

e a “how” or “why” question is being asked about o a contemporary set of events o over which a researcher has little or no control. To determine the questions that are the most pressing on a topic, as well as to gain some precision in formulating these questions, requires much preparation. One way is to review the literature on the topic (Cooper, 1984). Note that such a literature review is therefore a means to an end and not—as many people have been taught to think—an end in itself. Novices may think that the purpose of a literature review is to determine the answers about what is known on a topic; in contrast, experienced investigators review previous research to develop sharper and more insightful questions about the topic. Variations In Case Studies, But A Common Definition Our discussion has progressed without formally defining case study. In addition to a need for a definition, three commonly asked questions about variations in case studies still have to be addressed. For example, (1) Is it still a case study when more than one case is included in the same study? (2) Does a case study preclude the use of quantitative evidence? (3) Can a case study be used to do evaluations? Let us now attempt first to define the case study as a research method and then to address these three questions. Definition of the Case Study as a Research Method Some definitions of case studies have merely repeated the types of topics to which case studies have been applied. For example, in the words of one scholar, The essence of a case study, the central tendency among all types of case study, is that it tries to illuminate a decision or set of decisions: why they were taken, how they were implemented, and with what result. (Schramm, 1971, emphasis added) This definition thus cites cases of “decisions” as the major focus of case studies. Other common cases can include “individuals,” “organizations,” “processes,” “programs,” “neighborhoods,” “institutions,” and even “events.” However, dwelling on the definition of a case study by interest in an individual case, not by the methods of inquiry used (e.g., Stake, 2005, p. 443), would seem insufficient to establish the complete basis for case studies as a research method. Outside of social science research, notice that the everyday use of case studies in the popular literature and media (popular case studies—see the Preface) further blurs the issue. In fact, many of the earlier social science textbooks failed to consider case studies as a formal method at all. As discussed previously, one common shortcoming was to consider case studies as the exploratory stage of some other

type of research method. Another definitional shortcoming had been to confuse case studies with doing “fieldwork,” as in participant-observation. Thus, early textbooks limited their discussion of case studies to descriptions of participant-observation or of fieldwork as a data collection process, without elaborating further on a definition of case study research (e.g., Kidder & Judd, 1986; Nachmias & Nachmias, 2014). In a historical overview of the case study in American methodological thought, Jennifer Platt (1992) explains the reasons for these treatments. She traces the practice of doing case studies back to the conduct of life histories, the work of the Chicago school of sociology, and casework in social work. She then shows how participant-observation emerged as a data collection technique, effectively eliminating any further recognition of case study research. Thus, she found ample references to case study research in methodological textbooks up to 1950 but hardly any references to case studies or to case study research in textbooks from 1950 to 1980 (Platt, 1992, p. 18). Finally, Platt explains how the first edition of this book (1984) definitively dissociated case study research from the limited perspective of only doing some kind of fieldwork. She then also showed how a renewed discussion of case study research began to emerge in textbooks, largely occurring from 1980 to 1989 and continuing thereafter. Case study research, in her words, had now come to be appreciated as having its own “logic of design . . . a strategy to be preferred when circumstances and research problems are appropriate rather than an ideological commitment to be followed whatever the circumstances” (Platt, 1992, p. 46). A twofold definition of case study as a research method. And just what is this research method? The critical features first appeared in earlier publications (Yin, 1981a, 1981b, and reproduced on the companion website, study.sagepub.com/yin6e), predating the first edition of this book. The resulting definition as it has evolved over the five previous editions of this book reflects a twofold definition. The first part begins with the scope of a case study, when doing case study research: 1. A case study is an empirical method that e investigates a contemporary phenomenon (the “case”) in depth and within its real-world context, especially when o the boundaries between phenomenon and context may not be clearly evident. In other words, you would want to do a case study because you want to understand a real-world case and assume that such an understanding