The existing generalized p-value approach, from statistical literature, is applied to assess noninferiority of an experimental treatment in a three-arm clinical trial including a placebo. Two generalized test functions (GTFs) are constructed and Monte Carlo simulations are used to compute the p-value. The GTFs perform well in terms of maintaining the Type-I error probabilities, and the power of the tests are shown to increase to 1 as both the sample size and the parameter denoting the fraction of the effect of the reference drug with respect to placebo increase. The generalized confidence intervals are shown to retain the coverage probabilities. A published dataset is re-analysed using the proposed test and the results are in agreement with earlier findings.
Keywords: Behrens–Fisher problem; Dirichlet distribution; Type-I error; coverage probability; generalized test function; noninferiority.