A longitudinal study is a research design that involves observing the same variables repeatedly over an extended period. This type of study can provide insights into how variables change over time and their relationship with each other. For example, the Hewett et al. study investigated whether excessive knee valgus during landing predicted knee injury risk in adolescent females over a season. Longitudinal studies can be further classified as cohort, panel, or trend studies, depending on their focus. Cohort studies follow a specific group over time, while panel studies observe a fixed sample. Trend studies examine changes in a population over time. Other related terms include cross-sectional study, observational study, and prospective study.
Longitudinal Study: A research design that involves observing the same variables, several times over a period of time.
Example, the study by Hewett et al. (1) is a type of longitudinal study called a "cohort study." This study investigated whether excessive knee valgus during landing was a predictor of knee injury risk in adolescent females over the course of a season.