A case study is a research methodology, typically seen in social and life sciences. Key Points A case study can be defined as an intensive study about a person, a group of people, or a unit, which is aimed to generalize over several units. A case study has also been described as an intensive, systematic investigation of a single individual, group, community, or some other unit in which the researcher examines in-depth data relating to several variables. Normally Selects one case for analysis at a time. Researchers describe how case studies examine complex phenomena in the natural setting to increase understanding of them. By collecting qualitative or quantitative datasets about the phenomenon, the researcher gains more in-depth insight into the phenomenon than would be obtained using only one type of data. True case study often integrates different perspectives and adopts the most consequent approach to the particular. Hence it can be concluded that the true case studies often integrate different perspectives, adopts the most consequent approach to the particular, and normally Selects one case for analysis at a time. Therefore statements B, D, and E are correct. Additional Information The steps when using case study methodology are the same as for other types of research. The first step is defining the single case or identifying a group of similar cases that can then be incorporated into a multiple-case study. A search to determine what is known about the cases is typically conducted. This may include a review of the literature, grey literature, media, reports, and more, which serves to establish a basic understanding of the cases and informs the development of research questions. Data in case studies are often, but not exclusively, qualitative in nature. In multiple-case studies, analysis within cases and across cases is conducted.​