What type of study evaluates participant changes over long periods?

The correct answer focuses on a longitudinal study, which is specifically designed to assess changes in participants over extended periods. This type of study involves repeated observations of the same variables, typically over a span of years or even decades. It allows researchers to track developments, changes, and trends within the same group of subjects, providing insight into how individuals or populations evolve over time.

Unlike cross-sectional studies, which only capture data at a specific point in time and compare different groups, longitudinal studies offer a richer understanding of temporary shifts and long-term outcomes. They help in identifying patterns, causal relationships, and the effects of various interventions across an extended timeframe.

Case studies, while detailed and informative regarding individual cases, do not typically provide the same breadth of data applicable across time as longitudinal studies, since they often focus on deep dives into particular instances rather than tracking multiple variables across years. Experimental studies involve controlled conditions to test hypotheses, but they do not primarily focus on long-term participant changes, nor do they monitor participants over extended periods like longitudinal studies do.