title: A note on data monitoring, incomplete data and curtailed testing.
abstract: A question often asked in a fixed sample size clinical trial is whether the final outcome has been determined before the data has been completely collected. Recent papers in this journal and elsewhere have considered this question from the viewpoint of curtailed testing. In this paper, a related concept, "the probability of reversal" of a test procedure, is described and associated least upper bounds are given that are pertinent to the issue. The results are also of relevance in assessing, at the end of the trial, whether missing data are of consequence in the test of significance.
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods*; D003625:Data Collection / Q000379:methods*; D003657:Decision Making; D006801:Humans; D011336:Probability; D011897:Random Allocation / Q000379:methods; D013997:Time Factors