Scientific Publications by FDA Staff

Stat Biopharm Res 2016 Jan 2;8(1):35-9

New generalized p-value approach for noninferiority analysis.

Koti KM

The underlying statistical exercise in some noninferiority studies is to test a composite null hypothesis of a nonzero difference in the means of two normally distributed populations. These noninferiority studies are often analyzed under equal variances assumption. Unequal variances frequently occur in practice. In this article, we propose a noncentral t-distribution-based generalized test for proving noninferiority in the presence of unequal variances. We provide a simple SAS IML code to calculate the new generalized p-value. We compare the new generalized p-value with that of the Student's central t-distribution-based Tsui–Weerahandi generalized test. We conclude that Tsui–Weerahandi generalized test is conservative.