What type of data is primarily used in case studies?

The correct answer is qualitative data because case studies focus on in-depth exploration and detailed understanding of an individual, group, or phenomenon. This method often involves collecting narrative information through interviews, observations, and other unstructured or semi-structured methods to capture the complexities and nuances of the subject being studied.

Qualitative data is essential in case studies as it allows researchers to delve into the experiences, motivations, and contextual factors influencing the case. This rich, descriptive data can lead to insights that are not easily quantified, making it particularly valuable in psychological research, where human behavior and experiences often do not lend themselves to straightforward numerical analysis.

Other types of data, such as quantitative data or experimental data, focus on numerical measurements and statistical analysis, which are typically not the primary focus of case studies. Surveys and questionnaires can yield qualitative data but are not inherently aligned with the in-depth, narrative approach that characterizes a case study.