title: Exact, conditional, and predictive power in planning clinical trials.
abstract: It is shown how the predictive power, which takes account of prior clinical opinion about treatment differences, can be extended to group sequential designs based on a range rather than point of equivalence. It is found that such design when averaged over the whole prior distribution seems to be most conservative in terms of probability of firm conclusion followed by the nonzero null hypothesis design. Planning a trial based on calculations of the "exact" power or zero null hypothesis design may result in a practically unacceptable probability of firm conclusion.
authors.affiliation: Faculty of Medicine, Kuwait University, Safat.
authors.forename: M A
authors.initials: MA
authors.lastname: Moussa
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods*; D006801:Humans; D016014:Linear Models; D010934:Planning Techniques; D011336:Probability; D012494:Sampling Studies; D013810:Therapeutic Equivalency