قارن الطرق

	البحث الطولي المقطعي	دراسة الأتراب
المجال	تصميم البحث	علم الأوبئة
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	1965–1968	Mid-20th century (formal epidemiological design codified ~1950s)
صاحب الطريقة	K. Warner Schaie; Paul B. Baltes	Doll & Hill (British Doctors Study, 1951); Snow (cholera, 1854)
النوع	Quantitative observational research design	Observational longitudinal study design
المصدر التأسيسي	Schaie, K. W. (1965). A general model for the study of developmental problems. Psychological Bulletin, 64(2), 92–107.	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641
الأسماء البديلة	cohort-sequential design, accelerated longitudinal design, mixed longitudinal design, cross-sequential design	longitudinal study, follow-up study, panel study, incidence study
ذات صلة	1	6
الملخص	Longitudinal cross-sectional research — also called cohort-sequential or accelerated longitudinal design — simultaneously follows multiple age cohorts over time, combining the depth of longitudinal tracking with the age-range efficiency of cross-sectional sampling. By overlapping cohorts at successive waves, researchers can disentangle age effects, cohort effects, and period effects far more rigorously than either pure design allows, and can compress the calendar time needed to study development across a wide age span.	A cohort study assembles a group of individuals who share a common starting point — typically freedom from the outcome of interest — and follows them over time to observe who develops the outcome. By comparing incidence rates between exposed and unexposed subgroups, researchers can estimate relative risk and absolute risk differences. Cohort studies are the gold-standard observational design for measuring disease incidence and establishing temporal relationships between exposure and outcome.