AN ALTERNATIVE TO THE USE OF 2-SIDED TESTS IN CLINICAL-TRIALS

There is a controversy in the literature concerning the use of one- an d two-sided tests in clinical trials. Some contend that, when the rese arch question relates to improved efficacy or safety, that is, the exp ected change is in one direction only, the hypothesis test should refl ect this by being one-sided. Others insist on the use of a two-sided t est in case a treatment difference in the opposite direction to that e xpected might turn up. We propose an alternative procedure to the two- sided test which also provides protection against overlooking a negati ve effect. The proposed procedure tests simultaneously for a positive difference and for equivalence. We illustrate the procedure by applyin g it to the results of a recent clinical trial.