Multiple comparisons of k binomial proportions

Comparisons of k independent binomial proportions are studied. Piegorsch (1991) compared the Studentized-range implementation of the Wald interval and the Bonferroni-adjusted interval, both of which performed poorly for small values of the true proportions. Agresti et al. (2008) showed that adding one pseudo observation of each type in forming the Wald interval, along with the Studentized-range implementation, greatly improved the performance. A new two-stage method of multiple comparisons (global test followed by pairwise tests) is proposed. For the pairwise tests, three procedures are proposed, which are the LSD type, modified LSD, and inverse-sine based. Simulation studies show that the new procedures have relatively high power and that the modified LSD and inverse-sine based procedures maintain the familywise error rate near the nominal level.