2–301 17 CASE STUDY Bent Flyvbjerg 1 [C]onduct has its sphere in particular circumstances. That is why some people who do not possess theoretical knowledge are more effective in action (especially if they are experienced) than others who do possess it. For example, suppose that someone knows that light flesh foods are digestible and wholesome, but does not know what kinds are light; he will be less likely to produce health than one who knows that chicken is wholesome. —Aristotle 2 WHAT IS A CASE STUDY? Definitions of “case study” abound. Some are useful, others not. Merriam-Webster’s dictionary (2009) defines a case study straightforwardly as follows: Case Study. An intensive analysis of an individual unit (as a person or community) stressing developmental factors in relation to environment. According to this definition, case studies focus on an “individual unit,” what Robert Stake (2008, pp. 119–120) calls a “functioning specific” or “bounded system.” The decisive factor in defining a study as a case study is the choice of the individual unit of study and the setting of its boundaries, its “casing” to use Charles Ragin’s (1992, p. 217) felicitous term. If you choose to do a case study, you are therefore not so much making a methodological choice as a choice of what is to be studied. The individual unit may be studied in a number of ways, for instance qualitatively or quantitatively, analytically or hermeneutically, or by mixed methods. This is not decisive for whether it is a case study or not; the demarcation of the unit’s boundaries is. Second, the definition stipulates that case studies are “intensive.” Thus, case studies comprise more detail, richness, completeness, and variance—that is, depth—for the unit of study than does cross- unit analysis. Third, case studies stress “developmental factors,” meaning that a case typically evolves in time, often as a string of concrete and interrelated events that occur “at such a time, in such a place” and that constitute the case when seen as a whole. Finally, case studies focus on “relation to environment,” that is, context. The drawing of boundaries for the individual unit of study decides what gets to count as case and what becomes context to the case. Against Webster’s commonsensical definition of case study, the Penguin Dictionary of Sociology (Abercrombie, Hill, & Turner, 1984, p. 34; and verbatim in the 1994 and 2006 editions) has for decades contained the following highly problematic, but unfortunately quite common, definition of case study: Case Study. The detailed examination of a single example of a class of phenomena, a case study cannot provide reliable information about the broader class, but it may be useful in the preliminary stages of an investigation since it provides hypotheses, which may be tested systematically with a larger number of cases. This definition is indicative of much conventional wisdom about case study research, which, if not directly wrong, is so oversimplified as to be grossly misleading. The definition promotes the mistaken view that the case study is hardly a methodology in its own right, but is best seen as subordinate to investigations of larger samples. Whereas it is correct that the case study is a “detailed examination of a single example,” it is wrong that a case study “cannot provide reliable information about the broader class.” It is also correct that a case study can be used “in the preliminary stages of an investigation” to generate hypotheses, but it is wrong to see the case study as a pilot Bent Flyvbjerg, 2011, "Case Study," in Norman K. Denzin and Yvonna S. Lincoln, eds., The Sage Handbook of Qualitative Research, 4th Edition (Thousand Oaks, CA: Sage, 2011), Chapter 17, pp. 301-316.