TEST FOR QUALITATIVE INTERACTION OF CLINICAL-SIGNIFICANCE

We generalize the problem of detecting qualitative interaction between treatments and subsets in a two treatment clinical trial to the more practical problem of detecting a qualitative interaction greater than a non-negative value d, corresponding to the minimal treatment differe nce of clinical significance. We develop a test based on simultaneous confidence intervals for the generalized problem under the assumption of normality. The proposed test is easy to implement, either by hand c alculation or through the use of virtually any existing statistical so ftware. We derive explicit power function for the proposed test and gi ve examples to illustrate the procedures. (C) 1997 by John Wiley & Son s Ltd.