Hypothetical situation. Consider a fictitious study based in two populations. Twenty-five percent of the individuals in both populations have a particular risk factor (p1 = p2 = 0.25). We randomly selected 3750 subjects from each population (n1 = n2 =

3750).

(a) These are large samples, so the sampling distribution of will be approximately Normal. What are the mean and standard deviation of the sampling distribution?

(b) What percent of repeated independent SRSs of the given sizes will have prevalence differences that fall in the range −0.02 to 0.02?