Using and Misusing Statistics

The common errors … are not due to an absence of knowledge of specialized statistical methods or of mathematical training, but usually to the tendency of workers to accept figures at their face value without considering closely the various factors influencing them-without asking themselves at every turn 'what is at the back of these figures?What factors may be responsible for this value?In what possible ways could these differences have arisen?'That is constantly the crux of the matter."-A. Bradford Hill, 1937 1 C omparison of the response of patient subgroups to proven therapy is fraught with danger.Whether considering the possible benefits of carotid endarterectomy in women, various antihypertensive therapies in very old patients, or ␤-adrenergic blockade in black patients, the results of randomized studies may be inconclusive.