This study tested for a causal relationship between cognitive skills and the earnings disparities found among post-secondary graduates of different programs. The research was inspired by earlier work that established the higher incomes of engineering-, mathematics- and business-focused graduates relative to those of their arts- or humanities-focused counterparts.

The report used students’ performances in high school subjects (specifically English, science and math) to estimate their overall cognitive skills prior to completing post-secondary studies. After controlling for academic performance and other covariates, the author found that differences in high school performance did not explain the associated differences in wage outcomes independent from the choice of field of study.

The report concludes that, rather than cognitive differences, it may be supply and demand conditions that explain the earnings disparities among the studied fields.