विधियों की तुलना करें

	पूर्वव्यापी कॉक्स आनुपातिक जोखिम	पूर्वव्यापी कोहॉर्ट अध्ययन
क्षेत्र	महामारी विज्ञान	महामारी विज्ञान
परिवार	Process / pipeline	Process / pipeline
उद्भव वर्ष	1972	Mid-20th century (widely formalized 1950s–1970s)
प्रवर्तक	David R. Cox	Systematic use attributed to early 20th-century occupational epidemiology; formalized in modern epidemiological theory by Brian MacMahon and others
प्रकार	Semi-parametric survival regression	Observational analytic study
मौलिक स्रोत	Cox, D. R. (1972). Regression models and life-tables. Journal of the Royal Statistical Society, Series B, 34(2), 187–220.	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641
उपनाम	Cox PH regression (retrospective), retrospective Cox survival model, retrospective hazard regression, Cox model on historical data	historical cohort study, non-concurrent cohort study, retrospective follow-up study, historical prospective study
संबंधित	5	6
सारांश	Retrospective Cox proportional hazards regression applies Cox's (1972) semi-parametric survival model to time-to-event data extracted from existing records — medical charts, administrative databases, registries, or biobanks. It estimates covariate-adjusted hazard ratios (HRs) without specifying the underlying baseline hazard, making it the dominant analytic tool when the investigator works backward from already-recorded outcomes and exposures.	A retrospective cohort study assembles a group of individuals who share a common starting point and reconstructs their exposure history and subsequent outcomes entirely from pre-existing records. Because the data have already been collected before the study begins, the design is far faster and cheaper than a prospective cohort; however, the researcher must work with whatever information was recorded at the time rather than collecting purpose-built measurements.