What research method focuses on studying developmental changes over time?

The focus of a longitudinal study is to observe and analyze developmental changes over time by following the same subjects across different stages of their life or development. This method allows researchers to examine how individuals grow and change, looking for patterns and trends in various domains, such as cognitive, emotional, or physical development. By collecting data from the same participants at multiple points, researchers gain insights into the stability and variability of development within individuals, which can reveal important causal relationships and developmental trajectories.

Longitudinal studies are particularly valuable in developmental psychology as they can track changes that occur due to maturation, experiences, or environmental influences, providing a rich dataset that helps understand how and why individuals evolve over time. This method's depth makes it distinct from other approaches, which do not capture the same breadth of individual change over time.