THE QUEST FOR POWER - CONTRADICTORY HYPOTHESES AND INFLATED SAMPLE SIZES

To have the ''power'' of avoiding undersized clinical trials, the cust omary statistical strategy used in the past few decades is aimed at re jecting both a null stochastic hypothesis and a contradictory alternat ive hypothesis. This approach gives a trial the ''power'' to confirm t he ''insignificance'' of differences much smaller than the large value of delta desired in trials done to show efficacy. In many instances, however, a prime problem is that the current ''double-significance'' a pproach produces sample sizes 2-3 times larger than needed for stochas tic confirmation of large differences (greater than or equal to delta) . The inflated sample sizes and consequent problems can be avoided if a realistic value for delta is chosen and maintained thereafter, and i f an adequate ''capacity'' is calculated for ''single significance.'' (C) 1998 Elsevier Science Inc.