Case Studies

Although much of what we know about the empirical world has been generated by case studies and case studies continue to constitute a large proportion of work generated by the political science discipline, the case study method is poorly understood. Even among its defenders, there is confusion over the virtues and vices of this research design. Practitioners continue to ply their trade but have difficulty articulating what it is they are doing, methodologically speaking. The case study survives in a curious methodological limbo. The problem of ambiguity begins with the term itself. To refer to a work as a case study might mean that its method is qualitative, small N; that the research is holistic and thick (a more or less comprehensive examination of a phenomenon); that it uses a particular type of evidence (e.g., ethnographic, clinical, nonexperimental, non–survey based, participant observation, process tracing, historical, textual, or field research); that its method of evidence gathering is naturalistic (a “real-life context”); that the research investigates the properties of a single observation; or that the research investigates the properties of a single phenomenon, instance, or example. This entry presents a more precise definition of this method and discusses its strengths and limitations.

Evidently, researchers have many things in mind when they talk about case study research. Confusion is compounded by the existence of a large number of near synonyms—single unit, single subject, single case, N = 1, case based, case–control, case history, case method, case record, case work, clinical research, and so forth. As a result of this profusion of terms and meanings, proponents and opponents of the case study marshal a wide range of arguments but do not seem any closer to agreement than when this debate was first broached several decades ago. To talk about this subject in a productive fashion, we must arrive at a narrower definition. In this entry, we stipulate that a case connotes a spatially delimited phenomenon (a unit) observed at a single point in time or over some period of time. It comprises the sort of phenomena that an inference attempts to explain. Thus, in a study that attempts to explain certain features of nation-states, cases consist of nation-states (across [Page 194]some temporal frame). In a study that attempts to explain the behavior of individuals, individuals make up the cases. And so forth. Each case may provide a single observation or multiple (within-case) observations.

For students of political science, the archetypal case is the dominant political unit of our time, the nation-state. However, the study of smaller social and political units (regions, cities, villages, communities, social groups, and families) or specific institutions (political parties, interest groups, and businesses) is equally common in other subfields and, perhaps, increasingly so in comparative politics. Whatever the chosen unit, the methodological issues attached to the case study have nothing to do with the size of the individual cases. A case may be created out of any phenomenon so long as it has identifiable boundaries and comprises the primary object of an inference. Note that the spatial boundaries of a case are often more apparent than its temporal boundaries. We know, more or less, where a country begins and ends, even though we may have difficulty explaining when a country begins and ends. Yet some temporal boundaries must be assumed. This is particularly important when cases consist of discrete events—crises, revolutions, legislative acts, and so forth—within a single unit. Occasionally, the temporal boundaries of a case are more obvious than its spatial boundaries. This is true when the phenomena under study are eventful but the unit undergoing the event is amorphous. For example, if one is studying terrorist attacks, it may not be clear how the spatial unit of analysis should be understood, but the events themselves may be well bounded. Following this understanding of “case,” a case study could be defined as the intensive study of a single case for the purpose of understanding a larger population of cases. Several implications flow from this definition, as applied to the social sciences.

...