Non-differential misclassification of exposure always leads to an underestimate of risk: an incorrect conclusion.

Underlying (or true) relative risk set within the computer program to be 1-5; RR (actual) = relative risk provided by the simulation if all misclassification of exposure is removed; RR (apparent) = relative risk provided by the simulation with misclassification present (apparent relative risk).t These trials are based on the same values of r,, r2, P. and P2; slightly different results are obtained because each row summarises independent sets of 5000 simulations.