Fleming procedure (or O’Brien-Fleming multiple testing procedure) is a simple multiple testing procedure for comparing two treatments when the response to treatment is dichotomous. This procedure is used in clinical trials.
The procedure provides an opportunity to terminate the trial early when one treatment performs markedly better than the other. The procedure is based on a test statistic which is the usual chi-square statistic based on all data collected to that point, but provides an adjustment for the p-values obtained in each test, to ensure that Type I error is controlled.