title: Sample size in the planning and interpretation of clinical trials.
abstract: An understanding of sample size determination is important in both planning and interpreting the results of clinical trials. A Type II error occurs when it is concluded that there is no difference between treatment groups, when in truth there is a difference. Such a false negative conclusion results from too few patients in a trial. In this review the principles of estimating sample size before a trial is commenced and evaluating the results of a negative completed trial are reviewed. Clinically relevant examples are used to illustrate these concepts.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: M N
authors.initials: MN
authors.lastname: Levine
authors.forename: J
authors.initials: J
authors.lastname: Hirsh
mesh_terms: D001699:Biometry; D002986:Clinical Trials as Topic / Q000379:methods*; D006801:Humans; D012494:Sampling Studies