Abstract
The SPM+ was administered on a sample of 5189 school children from Sudan in 2016. Data about age, sex, locality, school type and stage, parental education and profession, family size and birth order were collected. Results for intelligence are congruent with the literature, giving the sample a mean IQ of ≈80 on British norms. Sex-differences are largely negligible. Differences in intelligence were found between three locations and are consistent with differences in parental education and income. Family income is a better predictor than parental education for children's intelligence. Children in private schools outperform children in public schools with mean IQs of 84–78 but path analysis points to a possible negative effect of private education. IQ-differences between age-groups and school-stages were found but no Simber-effect. The effects of selective processes along the educational pathway are shown and discussed with reference to the need for samples more representative for total populations.
•SPM+ administered on a Sudanese sample.•Strong internal consistency of the SPM+.•Age-differences in cognitive development are statistical artefacts caused by selective processes during educational pathways.•Income of family is the best predictor of children's test results.