Parental income and the fruits of labor: Variability in homework efficacy in secondary school.

Research in the sociology of education has shown that noncognitive traits are important predictors of educational outcomes and a mechanism of the intergenerational transmission of status. However, previous research on this topic typically posits that there is a constant effect of these traits with variable prevalences of these traits by socioeconomic status. Using time spent on homework as an example, I analyze income-based heterogeneity in homework efficacy, defined as the individual effect of study time on academic achievement, using a national U.S. probability sample of secondary students. Higher income students gain more knowledge from their homework time than their counterparts in all grades and all subjects except history, with greater group differences for math than for science and reading. These results are confirmed by models accounting for time-invariant unobserved heterogeneity in the 8th-10th, but not 10th-12th, grade windows. These results imply that increases in the amount of homework assigned may increase the socioeconomic achievement gap in math, science, and reading in secondary school.