Two binomial population proportions are suspected to be approximately 0.3, but they are unknown precisely. Using these as initial estimates, it is desired to conduct a study to determine the difference between these two population proportions. Obtain a general expression for the sample size n1 = n2 = n required in order to determine the difference p1 - p2 to within ±ξ with (1 - α) × 100% con?dence. In the speci?c case where ξ = 0.02 and α = 0.05 what is n?