title: Methodological issues in case-control studies. III--The effect of joint misclassification of risk factors and confounding factors upon estimation and power.
abstract: The effect of joint misclassification of polytomous risk factors and polytomous covariates in case-control studies upon estimation and power has been examined using computer simulation and mathematical models. It is concluded that non-differential misclassification of covariates may be as important as non-differential misclassification of exposure variables, and that the resultant bias of the relative risk estimate may be either toward or away from the null. It is pointed out that when a confounding variable is misclassified the calculated p value from the particular study will be incorrect and may either be too large or too small depending on the nature of the confounding.
mesh_terms: D002986:Clinical Trials as Topic; D003201:Computers; D004194:Disease / Q000145:classification*; D004812:Epidemiologic Methods; D006801:Humans; D008954:Models, Biological; D012107:Research Design; D012306:Risk