A method of stratifying the data according to the patterns of missing observations, summarizing each subject's repeated measurements by a summary measure and then comparing the treatment groups with the help of a distribution-free test based on the summary measure, is used here to compare the efficacy of tacrine dose regimens with that of placebo in a recent trial in Alzheimer's disease patients. The usefulness of the method of meta-analysis for comparing the treatment groups, in the presence of missing data, is also investigated.
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