Linganisha mbinu

	Utafiti wa Kesi-Udhibiti Retrospective uliowekwa ndani	Utafiti wa Cohort
Nyanja	Epidemiolojia	Epidemiolojia
Familia	Process / pipeline	Process / pipeline
Mwaka wa asili	1973 (formal description); widely adopted in epidemiology from 1980s onward	Mid-20th century (formal epidemiological design codified ~1950s)
Mwanzilishi	Nested case-control formalized by Mantel (1973); retrospective application via historical cohort records	Doll & Hill (British Doctors Study, 1951); Snow (cholera, 1854)
Aina	Observational analytic study design	Observational longitudinal study design
Chanzo asilia	Mantel, N. (1973). Synthetic retrospective studies and related topics. Biometrics, 29(3), 479–486.	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641
Majina mbadala	retrospective NCC, nested case-control within retrospective cohort, case-control nested in historical cohort, nested CCR	longitudinal study, follow-up study, panel study, incidence study
Zinazohusiana	5	6
Muhtasari	A retrospective nested case-control study is an efficient observational design in which cases and matched controls are sampled from within an already-assembled retrospective cohort. Exposure data are retrieved from historical records only for selected participants, dramatically reducing data-collection costs while retaining most of the analytic power of the full cohort. It is widely used in pharmacoepidemiology, occupational health, and disease-registry research.	A cohort study assembles a group of individuals who share a common starting point — typically freedom from the outcome of interest — and follows them over time to observe who develops the outcome. By comparing incidence rates between exposed and unexposed subgroups, researchers can estimate relative risk and absolute risk differences. Cohort studies are the gold-standard observational design for measuring disease incidence and establishing temporal relationships between exposure and outcome.