قارن الطرق

	دراسة الأتراب	بحث طولي
المجال	علم الأوبئة	تصميم البحث
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	Mid-20th century (formal epidemiological design codified ~1950s)	Late 19th–early 20th century; methodologically codified through the 20th century
صاحب الطريقة	Doll & Hill (British Doctors Study, 1951); Snow (cholera, 1854)	No single originator; foundational methodological treatments by Stuart Menard and Judith Singer & John Willett
النوع	Observational longitudinal study design	Quantitative (or mixed) observational research design
المصدر التأسيسي	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641	Menard, S. (2002). Longitudinal Research (2nd ed.). Sage Publications. ISBN: 978-0761922841
الأسماء البديلة	longitudinal study, follow-up study, panel study, incidence study	longitudinal study, longitudinal design, prospective longitudinal study, repeated-measures observational study
ذات صلة	6	4
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.	Longitudinal research is an observational design in which the same participants, groups, or units are measured repeatedly over an extended period. Rather than capturing a single snapshot, it tracks change, stability, and temporal sequencing of variables — making it the primary non-experimental strategy for studying development, growth, decline, and the unfolding of causal processes across time.