What is the difference between a longitudinal study and a cross-sectional study?

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 studyCross-sectional study
Repeated observationsObservations at a single point in time
Observes the same group multiple timesObserves different groups (a “cross-section”) in the population
Follows changes in participants over timeProvides snapshot of society at a given point