COMPARATIVE EFFICIENCY OF INFORMAL (SUBJECTIVE, IMPRESSIONISTIC) AND FORMAL (MECHANICAL, ALGORITHMIC) PREDICTION PROCEDURES - THE CLINICAL-STATISTICAL CONTROVERSY

Given a data set about an individual or a group (e.g., interviewer rat ings, life history or demographic facts, test results, self-descriptio ns), there are two modes of data combination for a predictive or diagn ostic purpose. The clinical method relies on human judgment that is ba sed on informal contemplation and, sometimes, discussion with others ( e.g., case conferences). The mechanical method involves a formal, algo rithmic, objective procedure (e.g., equation) to reach the decision. E mpirical comparisons of the accuracy of the two methods (136 studies o ver a wide range of predictands) show that the mechanical method is al most invariably equal to or superior to the clinical method: Common an tiactuarial arguments are rebutted, possible causes of widespread resi stance to the comparative research are offered, and policy implication s of the statistical method's superiority are discussed.