قارن الطرق

	دراسة الأتراب	دراسة الأتراب الاستشرافية
المجال	علم الأوبئة	علم الأوبئة
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	Mid-20th century (formal epidemiological design codified ~1950s)	1950s (systematic application); conceptual roots earlier
صاحب الطريقة	Doll & Hill (British Doctors Study, 1951); Snow (cholera, 1854)	Richard Doll and Austin Bradford Hill (landmark application, 1951-1954); cohort methodology formalised by modern epidemiology textbooks
النوع	Observational longitudinal study design	Observational longitudinal study design
المصدر التأسيسي	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641
الأسماء البديلة	longitudinal study, follow-up study, panel study, incidence study	longitudinal cohort study, prospective follow-up study, incidence study, prospective observational cohort
ذات صلة	6	6
الملخص	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.	A prospective cohort study assembles a group of participants who are free of the outcome of interest at baseline, measures their exposures, and then follows them forward in time to record who develops the outcome. By collecting exposure data before outcomes occur, it establishes a clear temporal sequence that supports causal inference — a major advantage over retrospective designs. It is the cornerstone observational method in epidemiology and clinical research.