Multiple-Case Designs

Conceptual Overview and Discussion

Multiple-case design, or the use of collective case studies, involves the extensive study of a number of instrumental case studies. The cases are carefully selected to develop a better understanding of the issue or to theorize about a broader context. The researcher may choose cases that are alike in order to analyze findings across similar cases. This is somewhat similar to a multiple experiment and follows replication logic. A mix of negative and positive cases may be chosen in order to examine variations and differences between the cases. Multiple-case design allows examination of processes and outcomes across many cases, identification of how individual cases might be affected by different environments, and the specific conditions under which a finding might occur. It may also help to form more general categories of how the specific conditions might be related. This makes the results more powerful than those from a single case and demonstrates the issues across a more varied range of circumstances than a single case can provide. The generalizability is enhanced relative to a single case. Examining the issues across cases can help to provide a tougher test of a theory. Therefore, multiple-case designs are more powerful than single-case designs in this respect, and more extensive descriptions and explanations of the issues are developed.

Application

Case study research involves extensive data collection with multiple forms of data. The data collection may include a combination of document analysis, in-depth interviews, participant observation, oral histories, multimedia, situation analysis, or be a clinical case study. The data collection is pointed in focus and provides rich, detailed, and in-depth information

There are two procedures in multiple-case design. The first is a parallel design where all of the case studies are selected in advance and are conducted at the same time. This may require the participation of a number of different researchers or investigators. The second is a sequential design where the case studies follow each other. The selection of each case study is informed by the outcome of the previously completed case. The cases may also incorporate a time dimension. Retrospective cases look at historical information. Prospective cases examine changes over time, and events as they occur.

According to Robert Yin, well known in the field of qualitative research, there are three case [Page 583]study designs in multiple case studies in which multiple case studies are actual replications. Exploratory case studies are conducted before a research question is identified; they typically have some organizational framework. Exploratory case studies are seen as a prelude to a large study and may be a pilot study. Explanatory case studies are the causal case studies in which the information from the cases is related to a theoretical position. Descriptive case studies follow a descriptive theory throughout the study.

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