Education, occupation, intelligence, and the regression paradox: A comment on Sak et al. (2026)

Based on statistically significant adjusted effects in multiple regression models, Sak et al. concluded that parental education and occupational status have independent additive effects on children’s intelligence over and above the contribution of the other. However, we show that the same data could be interpreted to support the paradoxical conclusion that low parental education or occupational status may counteract a low value on the other and help offspring to have the same intelligence as children with parents with higher education or occupational status. This is an example of the regression paradox which indicates that observed adjusted regression effects may be spurious. Hence, the conclusions by Sak et al. may be challenged. We recommend researchers to scrutinize their adjusted regression effects. If analyses identify the presence of the regression paradox, caution is advised and confident conclusions should be postponed.