Which method in psychology focuses on an in-depth analysis of a single individual?

The method that focuses on an in-depth analysis of a single individual is the case study. This approach allows researchers to explore the complexities of a person's life, behavior, and experiences in great detail. By using various data collection methods such as interviews, observations, and review of records, a case study provides rich qualitative data that can reveal insights into psychological conditions, personality traits, and behavior patterns.

This method is particularly useful for studying rare or unique phenomena that may not be easily captured in larger-scale studies. It enables psychologists to understand the nuances of individual experiences and the context surrounding those experiences, making it a valuable tool in clinical settings or when exploring theoretical concepts in depth.

In contrast, experimental research typically involves manipulating variables and measuring outcomes across larger groups to determine causality. Surveys aim to collect data from many individuals to generalize findings, while longitudinal studies involve repeated observations of the same individuals over time to detect changes or developments. These methods serve different purposes and do not focus on the in-depth exploration of a single individual as the case study does.