قارن الطرق

	دراسة بيئية بأثر رجعي	دراسة بيئية
المجال	علم الأوبئة	علم الأوبئة
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	20th century (formalized ~1980s–1990s)	19th century (Snow 1854); formalised mid-20th century
صاحب الطريقة	Epidemiological tradition; formalized by Morgenstern and others	Various; foundational work by John Snow (1854) and systematised in modern form by Brian MacMahon and colleagues
النوع	Observational epidemiological design	Observational epidemiological study
المصدر التأسيسي	Morgenstern, H. (1998). Ecologic studies. In K. J. Rothman & S. Greenland (Eds.), Modern Epidemiology (2nd ed., pp. 459–480). Lippincott-Raven.	Morgenstern, H. (1995). Ecologic studies in epidemiology: concepts, principles, and methods. Annual Review of Public Health, 16(1), 61–81.
الأسماء البديلة	retrospective aggregate study, historical ecological study, retrospective correlational ecological design, population-level retrospective study	aggregate study, correlational study, ecological correlation study, population-level study
ذات صلة	5	5
الملخص	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.	An ecological study is an observational epidemiological design in which the unit of analysis is a group or population — a country, region, city, or time period — rather than an individual. Exposures and outcomes are measured as aggregates (rates, proportions, or means) and then correlated across groups to generate or evaluate hypotheses about population-level associations between risk factors and disease.