This morning Stuart Ritchie shared a preprint of a new meta-analysis he made together with Elliot Tucker-Drob and the theme is very relevant in many of the present discussions about education: the link between IQ and education. An important insight from the conclusion:
…the results support the hypothesis that education has a causal effect on intelligence test scores. The effect of one additional year of education—contingent on study design, inclusion of moderators, and publication bias correction—was estimated from approximately one to five points on the standard IQ scale.
And this is also important:
The results reported here indicate strong, consistent evidence for effects of education on intelligence. Although the effects—on the order of a few IQ points for a year of education— might be considered small, at the societal level they are potentially of great consequence. A crucial next step will be to uncover the mechanisms of these educational effects on intelligence, in order to inform educational policy and practice.
Still important questions remain. Ritchie and Tucker-Drob mention several, but I personally find this question very relevant for further research:
…are there individual differences in the magnitude of the educational effect? One possibility is the “Matthew Effect” (Stanovich, 1986), whereby children at greater initial cognitive (or socioeconomic) advantage benefit more from additional education than those at lower advantage. Another possibility is that education acts as an “equalizer”, such that those at lower levels of initial advantage benefit most (Downey, von Hippel, & Broh, 2004). Indeed, some evidence of an equalizing effect was reported in a single study by Hansen, Heckman, & Mullen (2004).
Read the abstract:
Intelligence test scores and educational duration are positively correlated. This correlation can be interpreted in two ways: students with greater propensity for intelligence go on to complete more education, or a longer education increases intelligence. We meta-analysed three categories of quasi-experimental studies of educational effects on intelligence: those estimating education-intelligence associations after controlling for earlier intelligence, those using compulsory schooling policy changes as instrumental variables, and those using regression-discontinuity designs on school-entry age cutoffs. Across 142 effect sizes from 42 datasets involving over 600,000 participants, we found consistent evidence for beneficial effects of education on cognitive abilities, of approximately 1 to 5 IQ points for an additional year of education. Moderator analyses indicated that the effects persisted across the lifespan, and were present on all broad categories of cognitive ability studied. Education appears to be the most consistent, robust, and durable method yet to be identified for raising intelligence.