So sánh phương pháp

	Nghiên cứu dịch tễ học cắt ngang hồi cứu	Nghiên cứu sinh thái
Lĩnh vực	Dịch tễ học	Dịch tễ học
Họ	Process / pipeline	Process / pipeline
Năm ra đời	Mid–late 20th century	19th century (Snow 1854); formalised mid-20th century
Người khởi xướng	Epidemiology tradition (formalized in mid-20th century; Rothman, Greenland and others)	Various; foundational work by John Snow (1854) and systematised in modern form by Brian MacMahon and colleagues
Loại	Observational study design	Observational epidemiological study
Công trình gốc	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641	Morgenstern, H. (1995). Ecologic studies in epidemiology: concepts, principles, and methods. Annual Review of Public Health, 16(1), 61–81.
Tên gọi khác	retrospective cross-sectional survey, record-based cross-sectional study, retrospective prevalence study, secondary-data cross-sectional study	aggregate study, correlational study, ecological correlation study, population-level study
Liên quan	5	5
Tóm tắt	A retrospective cross-sectional epidemiological study measures the prevalence of exposures and outcomes at a single analytical time point using data that were originally recorded in the past — such as medical records, administrative databases, or disease registries. It combines the snapshot logic of a cross-sectional design with the efficiency of retrospective data access, making it a practical choice when prospective data collection is unfeasible or when large existing datasets are available.	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.