Putting Spearman’s Hypothesis to Work: Job IQ as a Predictor of Employee Racial Composition

Abstract

Job complexity and employee intelligence covary strongly. Likewise, race differences exist on mean IQ / g scores. Spearman's hypothesis predicts that race differences on cognitive tests are mainly g differences, and that the former should covary with how well mental tests measure the latter. Here we use jobs as "mental tests," and predict that as job IQ increases, the percent of White and Asian workers will increase, while the percent of Black workers will decrease. We found moderate to strong support for Spearman's hypothesis across these three racial groups. We also found a very large correlation (.86) between job IQ and complexity, as measured by the U.S. Federal Government's Dictionary of Occupational Titles classification scheme. In sum, like different mental tests, different jobs are more or less g-loaded. And, consistent with Spearman's hypothesis, the g-loading of a job predicts its demographic composition.

A longitudinal meta-analysis of range restriction estimates and general mental ability validity coefficients: Better addressing overcorrection amid decline effects.

“…For instance, studies show people with similar cognitive ability and vocational interests opt for similar jobs (Lancaster et al, 1994), and substantial differences exist in Grade Point Average-a common proxy for GMA (Ployhart & Holtz, 2008)-among different applicant pools (Connerley et al, 2003). Furthermore, Data and People from the DOT can predict 76% of the variance around GMA means (Pesta & Poznanski, 2016). Therefore, GMA relevance for performance implies means should differ among occupations, leading to decreased heterogeneity as those within occupations become more alike.…”