What is "case study"

n. research performed in detail on a single individual, group, incident or community, as opposed to, for instance, a sample of the whole population.

1. n. a careful study of some social unit (as a corporation or division within a corporation) that attempts to determine what factors led to its success or failure

2. a detailed analysis of a person or group from a social or psychological or medical point of view

A case study is about a person, group, or situation that has been studied over time. If the case study for instance, is about a group, it describes the behavior of the group as a whole, not behavior of each individual in the group.

Case studies can be produced by following a formal research method. These case studies are likely to appear in formal research venues, as journals and professional conferences, rather than popular works. The resulting body of 'case study research' has long had a prominent place in many disciplines and professions, ranging from psychology, anthropology, sociology, and political science to education, clinical science, social work, and administrative science.

In doing case study research, the "case" being studied may be an individual, organization, event, or action, existing in a specific time and place. For instance, clinical science has produced both well-known case studies of individuals and also case studies of clinical practices. However, when "case" is used in an abstract sense, as in a claim, a proposition, or an argument, such a case can be the subject of many research methods, not just case study research.

Thomas offers the following definition of case study:

"Case studies are analyses of persons, events, decisions, periods, projects, policies, institutions, or other systems that are studied holistically by one or more method. The case that is the subject of the inquiry will be an instance of a class of phenomena that provides an analytical frame — an object — within which the study is conducted and which the case illuminates and explicates."

According to J. Creswell, data collection in a case study occurs over a "sustained period of time."

One approach sees the case study defined as a research strategy, an empirical inquiry that investigates a phenomenon within its real-life context. Case-study research can mean single and multiple case studies, can include quantitative evidence, relies on multiple sources of evidence, and benefits from the prior development of theoretical propositions. As such, case study research should not be confused with qualitative research, as case studies can be based on any mix of quantitative and qualitative data. Similarly, single-subject research might be taken as case studies of a sort, except that the repeated trials in single-subject research permit the use of experimental designs that would not be possible in typical case studies. At the same time, the repeated trials can provide a statistical framework for making inferences from quantitative data.

The case study is sometimes mistaken for the case method used in teaching, but the two are not the same.