Robust and bootstrap testing procedures for bioequivalence.

A common problem encountered in bioequivalence studies is the presence of outliers. In this situation, the two one-sided t-tests proposed by Schuirmann fail to provide reasonable power for concluding bioequivalence. In contrast, our proposed 2 beta trimmed-t procedure has the following advantages: (1) it has higher efficiency for nonnormal symmetric distributions, (2) it is resistant to outliers, and (3) it is relatively easy to compute. Two bootstrap procedures introduced here provide further justification for the proposed trimmed t-test procedure. Results from Monte Carlo studies illustrate the power of the proposed procedures under various distributional assumptions for a 2 x 2 crossover trial.