With an increasing number of new chemical and biological preparations on the market, the screening of some 50,000 chemicals for cancer annually, the development of new dosage recommendations for older pharmacological products, and the relentless effort to discover causes of disease, the medical profession is faced with the problem of having to rely on studies that produce results in a relatively short period of time. Unfortunately, medical research has not developed enough to operate at a fast pace and still remain reasonably accurate. Even in areas where the need for results is less pressing, sufficient research money is available to make almost any study acceptable regardless of its objectives and design. The net effect is to foster research that may direct attention to wrong avenues of approach and retard progress in a field in which it is most needed. Thus, it has become exceedingly important that investigators exercise more care