Ethics of Randomized Clinical Trials from Statistician’sPerspective II. When Should the Randomization be Stopped or Modified?

Overview

The ethical responsibility to the randomized study participants demands that the results be monitored during thecourse of the trial. The interim evaluation of the trial results may lead to the premature stopping. However, therepeated statistical testing inflates the probability of false positive error. Hence statistical adjustments are necessary.The probabilistic rules for the random allocation of patients may be changed during the course of the trial accordingto the observed responses.

Key words:
randomized clinical trial, statistics, ethics, interim analyses, study monitoring.