Which method allows researchers to study the effects of aging over time?

A longitudinal study is a research method that involves repeated observations of the same variables, such as a group of individuals, over a long period. This approach is particularly useful for studying the effects of aging because it allows researchers to track the same participants over time, documenting changes and trends in behavior, cognition, and physical health as individuals age. By following the same group, researchers can better understand how aging impacts various aspects of life, providing insights that are more difficult to achieve with other methods.

In contrast, a cross-sectional study examines different participants at one point in time, which can highlight differences across age groups but does not demonstrate how individuals change over time. A snapshot study, while not a formal research method, often refers to a quick assessment or analysis at a specific moment. Lastly, a case study focuses on an in-depth analysis of a single instance or individual, limiting the ability to generalize findings about aging across a broader population.