Case studies are an important empirical research method, which has been increasingly becoming popular in software engineering discipline. According to Robert Yin, a case study is "an empirical inquiry that investigates a contemporary phenomenon within its real-life context, especially, when the boundaries between phenomenon and context are not clearly evident." The case studies research method requires special attention to completeness in observation, reconstruction, and analysis of the cases being studied.

Case studies can be single or multiple-case design with the latter kind of design having multiple cases of replication. Another categorization of case studies can be based on their objectives: exploratory, explanatory, and descriptive. Each of these kinds of case studies can be a single or multiple-case study. Exploratory case studies can be carried out without having a precise definition of the research questions and/or hypotheses. In an exploratory case study, pattern-matching procedure is used to compare the patterns found in the selected cases with some idealized theoretical pattern. The explanatory case study is usually performed for identifying cause-effect kind of relationships. In descriptive case studies, a researcher usually starts with some descriptive theory with an objective of forming hypotheses of cause-and-effect relationships as the result of the case study. There can be at least six sources from where the evidence can be gathered during a case study: documents, archival records, interviews, direct observation, participant-observation, and physical artifacts.