Sample size in the planning and interpretation of clinical trials.
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.
Levine
M N
MN
Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
Hirsh
J
J
D001699:Biometry; D002986:Clinical Trials as Topic / Q000379:methods*; D006801:Humans; D012494:Sampling Studies