What is the defining characteristic of a case study?

A case study is characterized by its focus on depth rather than breadth. This means it delves into extensive detail about a single unit or a small number of units, allowing for a comprehensive understanding of the case in question. This approach is essential in disciplines such as psychology, sociology, and medicine, where the individuality of the case can lead to insights that might not be captured in larger, more generalized studies. By concentrating on specific instances, researchers can explore complexities, contextual factors, and various dynamics that help provide a richer narrative and analysis of the subject matter.

In contrast, the other choices indicate different methodologies. Providing breadth of knowledge by exploring many similar cases does not align with the in-depth nature of a case study. Also, suggesting that a case study is suitable for widespread phenomena indicates a focus on generalizations, which runs counter to the specialized insights obtained from a case study. The final choice hints that while a case study offers detailed descriptions, it implies a limitation in applicability, but the strength of a case study is precisely its ability to inform broader theories by examining individual or unique cases deeply.