방법 비교

	회고적 생태 연구	회고적 코호트 연구
분야	역학	역학
계열	Process / pipeline	Process / pipeline
기원 연도	20th century (formalized ~1980s–1990s)	Mid-20th century (widely formalized 1950s–1970s)
창시자	Epidemiological tradition; formalized by Morgenstern and others	Systematic use attributed to early 20th-century occupational epidemiology; formalized in modern epidemiological theory by Brian MacMahon and others
유형	Observational epidemiological design	Observational analytic study
원전	Morgenstern, H. (1998). Ecologic studies. In K. J. Rothman & S. Greenland (Eds.), Modern Epidemiology (2nd ed., pp. 459–480). Lippincott-Raven.	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641
별칭	retrospective aggregate study, historical ecological study, retrospective correlational ecological design, population-level retrospective study	historical cohort study, non-concurrent cohort study, retrospective follow-up study, historical prospective study
관련	5	6
요약	A retrospective ecological study examines associations between exposures and outcomes using pre-existing aggregate data from defined populations or geographic units. Rather than following individual subjects, the unit of analysis is a group — a country, region, or time period — and all measurements come from historical records already collected before the study began. It is a rapid, low-cost way to generate hypotheses about environmental, social, or policy determinants of disease at the population level.	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.