In which study design is data collected from the same set of individuals repeatedly over time?

The selected answer is appropriate because a panel study involves collecting data from the same individuals at multiple points in time. This design allows researchers to track changes and trends within the same group, providing insights into how specific variables or behaviors evolve over time. The richness of data derived from a panel study enhances the understanding of individual-level changes, making it a powerful tool in communication research and other fields.

In contrast, a cross-sectional study collects data at a single point in time from different individuals, which does not allow for tracking changes within the same subjects over time. A cohort study might look at particular groups sharing a common characteristic, often across different time frames, but it doesn’t always entail repeated measurements of the same individuals. A longitudinal study is a broader category encompassing any study that collects data from the same subjects over time, including panel studies, but the term 'panel study' specifically highlights the method of using a fixed group of individuals consistently.