Longitudinal studies and cross-sectional studies are two different types of research design. In a cross-sectional study you collect data from a population at a specific point in time; in a longitudinal study you repeatedly collect data from the same sample over an extended period of time.
Longitudinal study
Cross-sectional study
Repeated observations
Observations at a single point in time
Observes the same group multiple times
Observes different groups (a “cross-section”) in the population
Follows changes in participants over time
Provides snapshot of society at a given point