Perspectives on the statistician's role in cooperative clinical research

Some contributions which the statistician can make to cooperative research are briefly discussed in the hope of furthering communication between statistician and clinician. In the planning stages the major issues are those of sample size, randomization, data collection and early termination. Careful consideration of these points can help ensure that the main questions posed by the trial are answered as economically as possible. During the final stages the major statistical contribution is in analysis and presentation of results in a way which explores the interrelationships between the most important baseline and therapeutic factors and their joint effect on outcome.