General mental ability testing and adverse impact in the United Kingdom: a meta-analysis with more than two million observations

We review ethnic group differences on high-stakes General Mental Ability (GMA) tests based on 21st century UK data. Thereafter, we meta-analyse scores on 23 occupational, public sector, educational, military, or general-public selection tests, with a sample size exceeding two million. Relative to White GMA, the grand meta-analytic effect sizes (Cohen's d) by major ethnic groups were: Mixed d = .14 (k = 24, N = 67,114), Blacks d = .65 (k = 32, N = 112,975), Asians d = .33 (k = 32, N = 311,695), and Other d = .49 (k = 24, N = 42,846). Further, although Chinese residents outscored White British residents (d = −.15, k = 20, N = 18,897), all other Asian ethnic groups scored slightly to substantially lower. For example, South Asians as a whole averaged d = .37; k = 13, N = 67,566. By subgroups, these averages were: Indians (d = .17, k = 10, N = 28,236), Pakistanis (d = .49, k = 9, N = 19,371), and Bangladeshi (d = .55, k = 7, N = 19,772). Implications for practice and theory are discussed.