Role of mental abilities and mental tests in explaining high-school grades

It is well-known that some students earn higher grades than others; however, published research on the mental abilities that are correlated with high school grades is sparse. Two studies examined the relationship between different mental abilities and high school grades. Study 1 showed that the personality trait conscientiousness predicted high school grades (r = .32) almost as well as g (r = .37 to .40). In Study 2, the relationship between general mental ability (g) and high school grades was linear and fairness analyses indicated slight overprediction for Hispanics and Blacks and underprediction for females. Validity was lowered slightly by group preferences. With the exception of mathematical knowledge, the correlation between mental abilities and high school grades in both studies was largely attributable to g rather than specific abilities (s) measured by each test. Additional analyses showed that grade point averages are reliable and conscientiousness and g do not interact when predicting high school grades.