A NEW PROCEDURE FOR GROUP SEQUENTIAL-ANALYSIS IN CLINICAL-TRIALS

Since Pocock (1977, Biometrika 64, 191-199), many methods have been developed for group sequential analysis of clinical trials. However, these methods remain underemployed, partly because of inconsistencies of sequential testing [Berry (1987, The Statistician 36, 181-189)]. This paper considers a new approach, which, by requiring that a succession of interim analyses be significant at the alpha-level, both preserves the overall significance level a and does not present some of the inconsistencies of the previous methods. Results are obtained for a normal or binary response and for survival data. A comparison with the usual group sequential testing is also presented.