What must an epidemiologic study warrant?
• A study must warrant that its numerical representations of individual lifetime ETS exposure recalls are true measures of actual exposures. • A study must warrant that an exposure recall bias affects cases and control groups, and exposed and non-exposed groups at the same rate. • A study must warrant that subject selection and misclassification biases affect cases and control groups, and exposed and non-exposed groups at the same rate. • A study must warrant that known causal confounders affect cases and control groups, and exposed and non-exposed groups at the same rate. • A study must warrant the accuracy of pathological and diagnostic records. • The results from different studies addressing the same subject must be consistently reproducible. In any study, the statistical margin of error of reported risks should reach no less than the 95% level of significance. • If the above criteria are met, the results of a study should also be consistent with Hills criteria of causality. (See be
