مقایسهٔ روش‌ها

	مطالعه کوهورت	کارآزمایی بالینی تصادفی (RCT)
حوزه	اپیدمیولوژی	اپیدمیولوژی
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	Mid-20th century (formal epidemiological design codified ~1950s)	1948 (first rigorously conducted RCT — MRC streptomycin trial)
پدیدآور	Doll & Hill (British Doctors Study, 1951); Snow (cholera, 1854)	Austin Bradford Hill; MRC Streptomycin Trial team
نوع	Observational longitudinal study design	Interventional experimental study
منبع بنیادین	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641	Friedman, L. M., Furberg, C. D., DeMets, D. L., Reboussin, D. M., & Granger, C. B. (2015). Fundamentals of Clinical Trials (5th ed.). Springer. ISBN: 978-3319185385
نام‌های دیگر	longitudinal study, follow-up study, panel study, incidence study	RCT, randomized controlled trial, randomised controlled trial, clinical randomized trial
مرتبط	6	6
خلاصه	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 randomized clinical trial (RCT) is an experimental study design in which participants are randomly assigned to an intervention group or a control group, then followed prospectively to compare outcomes. Random allocation is the defining feature: it distributes known and unknown confounders across groups by chance, making the RCT the strongest individual study design for establishing causal efficacy of a treatment or intervention under controlled conditions.