A study that takes place over time, preferably with at least three time points so that change both between and within individuals can be charted.
See Auto-regressive models, Cohort, Cohort effect, Cross-lagged correlation/regression model, Cross-sectional design, Developmental research, Follow-bacjk design, Latent growth model, Longitudinal-experimental studies, Longitudinal studies, Microgenetic method, Multiple cohort study, Panel studies, Prodiction and retrodictions, Prospective cohort