Imagine that, in hypothetical study shown in table below, cases underestimated their exposure and, as a result, 20% of exposed cases were falsely categorized as unexposed, however that the classification of controls was not affected.

True results of the hypothetical case-control study with no measurement Error.

Explain whether this type of misclassification random or systematic? Is it differential or nondifferential?

b) What effect would it have over the results of study? Draw up a two-by-two table displaying the misclassification, then determines estimates of the risk ratio for both true and the misclassified results and make comment on their difference to illustrate the effect.