手法を比較

	前向きコホート研究	ランダム化比較試験 (RCT)
分野	疫学	疫学
系統	Process / pipeline	Process / pipeline
提唱年	1950s (systematic application); conceptual roots earlier	1948 (first rigorously conducted RCT — MRC streptomycin trial)
提唱者	Richard Doll and Austin Bradford Hill (landmark application, 1951-1954); cohort methodology formalised by modern epidemiology textbooks	Austin Bradford Hill; MRC Streptomycin Trial team
種類	Observational longitudinal study design	Interventional experimental study
原典	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
別名	longitudinal cohort study, prospective follow-up study, incidence study, prospective observational cohort	RCT, randomized controlled trial, randomised controlled trial, clinical randomized trial
関連	6	6
概要	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.	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.