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 Printable version |
The different types of epidemiological study |
Cahiers d'études et de recherches francophones / Santé . Volume 2, Number 1, 49-54, Janvier-Février 1992, Note méthodologique
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 Résumé
Article gratuit
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Author(s) : Jacques Drucker, Alain Moren, François Dabis |
Summary : Most epidemiological studies are observational and can be classified into three major types: case-control, cohort and transversal studies. As subjects cannot be randomly allocated to exposure or disease groups in any of these types of study, the investigator must pay particular attention to intergroup comparability. Case-control studies involve selection of subjects on the basis of disease status, while cohort studies are based on exposure status. Both approaches have advantages and disadvantages, which are discussed in this article. Observational studies are rarely able to demonstrate a direct causal relationship between exposure to a risk factor and the occurrence of a disease, even though a number of criteria, such as dose-effect, consistency, specificity, temporality and biological plausibility, have been established. Observational studies are therefore powerful methodological tools for the epidemiologist. |
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