Failures and successes are assumed to be observable for all 16 patients before the entry of patients begins in the next block. When the criterion for interrupting randomization is reached, all16 patients in the next block receive the suggestively superior treatment. Randomization resumes if the criterion is not met later on and, in any case, the trial continues until the final decisive test when the pre-planned number of patients is reached. The appropriate sample size to meet these specifications is about 224. This sample size is used in all 1,000 iterations of each trial simulation.
Interim results show no suggestive preference for either treatment.
112 Experimental Pts. 112 Experimental Pts. Late reversal of midway trend toward experimental preference. 112 Experimental Pts. Interim results show clear preference for experimental treatment, followed by exclusive assignment of experimental treatment.