National IQs and Socioeconomic Development

Using 47 indicators of socioeconomic development and various sources of performance on cognitive tests, we constructed the SDI (socioeconomic development index) and a set of national IQs for 197 nations, the latter using no geographic imputations. Combining the various datasets reduced the estimated standard error of national IQs from 5.41 to 2.58, and a strong correlation between socioeconomic development and national IQs was observed (r = .88). Based on the prior that Flynn Effect gains do not pass measurement invariance, IQ scores should exhibit some non-negligible bias between countries. Empirical assessments of measurement invariance across nations finds that measurement invariance violations are uncommon and typically found when verbal tests are given. In most countries, national IQs show high levels of reliability and validity, and we encourage their use in the literature.