In the social sciences and life sciences, a case study is a research method involving an up-close, in-depth, and detailed examination of a subject of study (the case), as well as its related contextual conditions. Although no single definition of the case study exists, 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. 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 the case is used in an abstract sense, as in a claim, proposition, or argument, such a case can be the subject of many research methods, not just a case study. Thomas offers the following definition of a 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 methods.
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. Case studies should not be confused with qualitative research and they can be based on any mix of quantitative and qualitative evidence.
Single-subject research provides the statistical framework for making inferences from quantitative case-study data. This is also supported and well-formulated in (Lamnek, 2005): “A case study is a research approach, situated between concrete data taking techniques and methodologic paradigms.” The case study is sometimes mistaken for the case method used in teaching, but the two are not the same.