The problem of group differences in ability test scores in employment selection

Abstract

Group differences on employment tests of cognitive abilities often lead to lower job selection rates for blacks and some other minorities, such as Hispanics. These lower selection rates are referred to as "adverse impact." This paper reviews measurement-based research efforts to solve or circumvent this problem. Cumulative research findings have disconfirmed three early theories that postulated that average score differences between groups were due to deficiencies in the tests: the theory of single group validity, the theory of differential validity, and the theory of test underprediction. At the same time, research has shown that such tests are valid for virtually all jobs and that failure to employ them in selection can lead to substantial economic losses. These findings have increased the percentage of jobs for which such tests will probably be used. Attempts to solve or circumvent the problem of group differences by redefining test (or selection) fairness, by relying on job experience to eliminate ability-related job performance differences, by use of specific aptitudes rather than general ability measures, and by searching for bias in job performance measures appear to have been unsuccessful. It is possible that use of certain nontest selection methods in combination with general mental ability measures may lead to some reduction in hiring rate differences. However, the reduction appears small, and the picture as a whole indicates that the problem of group differences and adverse impact is far more intractable than initially believed. Political, legal, and social policy decisions will determine how this problem is addressed. Measurement-based research has not solved the problem. Its major contribution has been to clarify the nature of the problem, and in this respect it has been very successful.