What type of study focuses on a single individual's in-depth examination?

A case study is a research method that involves an in-depth examination of a single individual or a small group of individuals. This approach allows researchers to explore complex phenomena in a detailed manner, providing insights that quantitative methods may overlook. By focusing on a single case, researchers can gather comprehensive data through various means such as interviews, observations, and psychological tests, leading to a rich understanding of that individual's experiences, behavior, and development.

This method is particularly effective in developmental psychology, as it allows for the exploration of unique developmental trajectories and personal histories. It accommodates the complexity of human life and can reveal patterns or insights that could inform broader theories and practices within the field.

In contrast, qualitative research encompasses various methods focused on understanding experiences and perspectives but is broader than just individual examinations. Longitudinal studies track the same individuals over time to understand changes and development, while cross-sectional studies compare different individuals or groups at a single point in time. They do not provide the same depth of understanding about a single individual as a case study does.