tailieunhanh - Comparative Efficiency of Informal (Subjective, Impressionistic) and Formal (Mechanical, Algorithmic) Prediction Procedures: The Clinical–Statistical Controversy

What can be determined from such a heterogeneous aggregation of studies, concern- ing a wide array of predictands and involving such a variety of judges, mechanical combination methods, and data? Quite a lot, as it turns out. To summarize these data quantitatively for the present purpose (see Grove et al., 2000, for details omitted here), we took the median difference between all possible pairs of clinical versus mechanical predictions for a given study as the representative outcome of that study. We converted all predictive accuracy statistics to a common metric to facilitate comparison across studies (., convert from hit rates to. | Psychology Public Policy and Law 1996 2 293-323 167 Comparative Efficiency of Informal Subjective Impressionistic and Formal Mechanical Algorithmic Prediction Procedures The Clinical-Statistical Controversy William M. Grove and Paul E. Meehl University of Minnesota Twin Cities Campus Given a data set about an individual or group . interviewer ratings life history or demographic facts test results self-descriptions there are two modes of data combination for a predictive or diagnostic purpose. The clinical method relies on human judgment that is based on informal contemplation and sometimes discussion with others . case conferences . The mechanical method involves a formal algorithmic objective procedure . equation to reach the decision. Empirical comparisons of the accuracy of the two methods 136 studies over a wide range of predictands show that the mechanical method is almost invariably equal to or superior to the clinical method Common antiactuarial arguments are rebutted possible causes of widespread resistance to the comparative research are offered and policy implications of the statistical method s superiority are discussed. In 1928 the Illinois State Board of Parole published a study by sociologist Burgess of the parole outcome for 3 000 criminal offenders an exhaustive sample of parolees in a period of years preceding. In Meehl 1954 1996 this number is erroneously reported as 1 000 a slip probably arising from the fact that 1 000 cases came from each of three Illinois prisons. Burgess combined 21 objective factors . nature of crime nature of sentence chronological age number of previous offenses in unweighted fashion by simply counting for each case the number of factors present that expert opinion considered favorable or unfavorable to successful parole outcome. Given such a large sample the predetermination of a list of relevant factors rather than elimination and selection of factors and the absence of any attempt at optimizing weights the .