Which type of study observes changes over time?

A longitudinal study is designed specifically to observe changes over time by collecting data from the same subjects repeatedly at different points in time. This approach allows researchers to track developments and shifts in variables, behaviors, or attitudes as they occur, providing valuable insights into trends and causal relationships. By following the same cohort over an extended period, longitudinal studies can offer a clearer understanding of how specific factors influence outcomes over time, making them particularly useful in fields like psychology, medicine, and social sciences.

In contrast, other study types do not focus on temporal changes in the same way. Cross-sectional studies analyze data at a single point in time, capturing a snapshot of a situation without tracking its evolution. Case studies involve an in-depth exploration of a particular instance or subject, but they do not systematically measure changes over time. Meta-analyses synthesize findings from multiple studies to draw broader conclusions but do not observe changes themselves within a dataset over time.