AP Psychology Practice Test

A longitudinal study is a type of observational research method where the same group of individuals is studied over an extended period of time. This means that the same people are observed and data is collected multiple times throughout the study period. Unlike other types of studies, such as cross-sectional studies that compare different groups at one particular time, a longitudinal study tracks changes and development within the same group. While comparing people of different ages at one time (Option A) or studying the aging process (Option B) may involve collecting data over a period of time, it is not the same as a longitudinal study. Similarly, Option D is incorrect because a longitudinal study is not specifically focused on the development of morality, but rather the development and changes in a particular group over time. Option C is the most accurate differentiator of a longitudinal study.