Linked from
The 23 pages that link to Longitudinal study, each with the reason it gives.
Observational studyRelated: Repeated observations can track changing exposures and outcomes.
Time seriesRelated: Its repeated measurements can produce time series for each subject.
Emil KraepelinRelated: He treated changes in symptoms and outcomes over time as diagnostic evidence.
Sex researchRelated: Repeated measurements can reveal how sexuality changes across the life course.