قارن الطرق

	دراسة الأتراب	دراسة الحالة والشاهد المتداخلة (Nested Case-Control Study)
المجال	علم الأوبئة	علم الأوبئة
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	Mid-20th century (formal epidemiological design codified ~1950s)	1973–1977
صاحب الطريقة	Doll & Hill (British Doctors Study, 1951); Snow (cholera, 1854)	Nathan Mantel (1973); D. C. Thomas (1977 formalization)
النوع	Observational longitudinal study design	Hybrid observational study design
المصدر التأسيسي	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641	Thomas, D. C. (1977). Addendum to: Methods of cohort analysis: Appraisal by application to asbestos mining. Journal of the Royal Statistical Society, Series A, 140(4), 469–491.
الأسماء البديلة	longitudinal study, follow-up study, panel study, incidence study	NCC study, nested CC design, case-control within cohort, density sampling case-control
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 nested case-control study is an efficient observational design embedded within a defined cohort. For each participant who develops the outcome of interest (a case), a small number of matched controls are sampled from those still at risk at the same point in time. This density-sampling strategy yields odds ratios that approximate incidence-rate ratios from the full cohort at a fraction of the data-collection cost — making it the preferred alternative when measuring exposures for all cohort members would be prohibitively expensive or technically demanding.