Intelligence and school grades: A meta-analysis

Intelligence is considered as the strongest predictor of scholastic achievement. Research as well as educational policy and the society as a whole are deeply interested in its role as a prerequisite for scholastic success. The present study investigated the population correlation between standardized intelligence tests and school grades employing psychometric meta-analysis (Hunter & Schmidt, 2004). The analyses involved 240 independent samples with 105,185 participants overall. After correcting for sampling error, error of measurement, and range restriction in the independent variable, we found a population correlation of ρ = .54. Moderator analyses pointed to a variation of the relationship between g and school grades depending on different school subject domains, grade levels, the type of intelligence test used in the primary study, as well as the year of publication, whereas gender had no effect on the magnitude of the relationship.