Which type of study primarily focuses on an individual or small group for detailed information?

The correct choice focuses on a case study, which is a research method that provides an in-depth, detailed understanding of a specific individual or small group. This approach allows researchers to explore complex issues, behaviors, or experiences more thoroughly than other methods. Case studies often involve various data collection techniques, such as interviews, observations, and analyses of historical documents, to gather rich qualitative data.

This method is particularly effective in psychology for understanding unique psychological phenomena, developing theories, or generating hypotheses, as it captures the nuances of human behavior and experiences that larger-scale studies may overlook. Because it focuses on depth rather than breadth, a case study offers comprehensive insights that broader studies might miss.

In contrast, experimental studies typically involve manipulating variables to identify cause-and-effect relationships, survey studies gather data from larger groups to measure attitudes or opinions, and longitudinal studies track the same subjects over time to observe changes and developments. Each of these approaches has its own strengths, but for obtaining detailed information about a specific individual or a small group, the case study is the most suitable choice.