Please no guesses! I will rate fairly and quickly! In a case-control study of smoking and lung cancer, researchers are concerned because participation rates were lower among eligible controls than among eligible cases (i.e., patients with lung cancer were more willing to participate in the study). When the researchers compared smoking rates among study participants and those who refused to participate, however, they found that rates were similar. What threat to validity is described in this scenario, if any? No threat Measurement bias Nondifferential misdassification of outcome Sampling error Selection bias A small cohort study of exercise and gestational diabetes (diabetes that developes during pregnancy) found that rates of gestational diabetes were not significantly different among women with low exercise levels as compared to women with high exercise levels (p=0.18). What threat to validity is described in this scenario, if any? Select one: Measurement bias Sampling error Solution 1-: C 2-: A Non differential misclassification is when all classes, groups, or categories of a variable (whether exposure, outcome, or covariate) have the same error rate or probability of being misclassified for all study subjects. The traditional assumption has been that, in the case of binary or dichotomous variables, this would result in an underestimate of the hypothesized relationship between exposure and outcome. This has more recently been challenged however in that results of individual studies represent a single estimate and not the average of repeated measurements and thus can be farther (or nearer) from the null value (i.e. zero) than the true value..