Knowledge that Transforms

We study the effects of peer gender composition in STEM doctoral programs on persistence and degree completion. Leveraging unique new data and quasi-random variation in gender composition across cohorts within programs, we show that women entering cohorts with no female peers are 11.7pp less likely to graduate within 6 years than their male counterparts. A 1 sd increase in the percentage of female students differentially increases women's probability of on-time graduation by 4.4pp. These gender peer effects function primarily through changes in the probability of dropping out in the first year of a Ph.D. program.

This study provides evidence on the relative effectiveness of computer-assisted learning (CAL) software and traditional teaching. Based on a field experiment in Salvadoran primary schools, we evaluate three interventions that aim to improve learning in mathematics: (i) additional teacher-led classes, (ii) additional CAL classes monitored by a supervisor, and (iii) additional CAL classes instructed by a teacher. We find that CAL lessons lead to larger learning gains and are less sensitive to class size as well as student ability than teacher-centered classes. Our results highlight the value of CAL in an environment with heterogeneous classes and poorly qualified teachers.

Pre-College human capital investment occurs within a competitive environment and depends on market incentives created by Affirmative Action (AA) in college admissions. These policies affect mechanisms for rank-order allocation of college seats, and alter the relative competition between blacks and whites. We present a theory of AA in university admissions, showing how the effects of AA on human capital investment differ by student ability and demographic group. We then conduct a field experiment designed to mimic important aspects of competitive investment prior to the college market. We pay students based on relative performance on a mathematics exam in order to test the incentive effects of AA, and track study efforts on an online mathematics website. Consistent with theory, AA increases average human capital investment and exam performance for the majority of disadvantaged students targeted by the policy, by mitigating so-called "discouragement effects." The experimental evidence suggests that AA can promote greater equality of market outcomes and narrow achievement gaps at the same time.

We estimate the nonlinear impact of class size on student achievement by exploiting regulations that cap class size at 20 students per class in kindergarten. Based on student-level information from a previously unexploited and unique large-scale census survey of kindergarten students, this study provides clear evidence of the nonlinearity of class size effects on development measures. While the effects are largest on cognitive development, class size reductions also improve noncognitive skills for children living in disadvantaged areas. These findings suggest that sizeable class size reductions targeted at disadvantaged areas would achieve better results than a marginal reduction across the board.

I estimate the effects of exposure to the Great Recession on employment and earnings for groups defined by year of birth over the 10 years following the beginning of the recession. Younger workers experience the largest earnings losses in percentage terms (up to 13%), in part because they remain less likely to work for high-paying employers even as their overall employment recovers more quickly than that of older workers.

In two 1992 papers, Card and Krueger used labor market outcomes to study the productivity of school spending. Following their lead, we examine the effects of post-1990 school finance reforms on students’ educational attainment and labor market outcomes. Using a state-by-cohort panel design, we find that reforms increased high school completion and college-going, concentrated among Black students and women, and raised annual earnings. The reforms also increased the return to education, particularly for Black students and men, driven by the return to high school.

Firms often impose constraints on working hours. While many believe that these constraints shape labor supply decisions, little evidence exists to support such views. We explore this relationship using linked employer-employee data on hours worked and the variation in tax rates derived from the 2010 Danish tax reform. We show that hours worked are unresponsive to individual tax changes in firms with strict constraints, whereas they respond to these changes, directly and through spillovers, in firms with looser constraints. Starting from these findings, we discuss the determinants of hours constraints, distinguishing between firms’ technologies and coordination of hours among coworkers.