Linganisha mbinu

	Utafiti wa Kiikolojia wa Retrospective	Utafiti wa Ikolojia
Nyanja	Epidemiolojia	Epidemiolojia
Familia	Process / pipeline	Process / pipeline
Mwaka wa asili	20th century (formalized ~1980s–1990s)	19th century (Snow 1854); formalised mid-20th century
Mwanzilishi	Epidemiological tradition; formalized by Morgenstern and others	Various; foundational work by John Snow (1854) and systematised in modern form by Brian MacMahon and colleagues
Aina	Observational epidemiological design	Observational epidemiological study
Chanzo asilia	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.
Majina mbadala	retrospective aggregate study, historical ecological study, retrospective correlational ecological design, population-level retrospective study	aggregate study, correlational study, ecological correlation study, population-level study
Zinazohusiana	5	5
Muhtasari	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.