Increasing the power of clinical trials through judgment analysis.

A method for increasing the statistical power of clinical trials to detect clinically important differences is described. Inconsistency in physicians' overall judgments of treatment effectiveness adds "noise" to a trial that may mask either the superiority or the inferiority of particular treatments. The method described here uses "judgment analysis" to reduce errors in an individual's overall judgments of treatment effectiveness. The method can also be used to reduce error variance due to differences in judgment between physicians and may thus be particularly useful in multicenter trials. The method is illustrated with results from a recent trial.