This study examines the past year relationship between GPA and experiencing a combination of two primary depression symptoms, feeling sad and losing interest in usual activities for at least two consecutive weeks, among high school students during 2001-2009. The GPA loss associated with sadness, as defined above, falls from slightly less than a plus/minus mark to around 0.1 point when commonly co-occurring behaviors are held constant. Nonetheless, this effect is significantly larger than those of having considered or planned suicide and equivalent to having attempted suicide, which seemingly signify more severe depression. Moreover, sadness lowers the probability of earning A grades, and raises that of receiving grades of C or below, by over 15%. Coefficient sizes are similar when comparison groups are restricted to students engaging in correlated behaviors and in matching and instrumental variable models, suggesting that sadness causally reduces academic performance.
