Researchers often exploit random allocation to groups to study peer effects. As groups get larger, estimates of peer effects become imprecise and amplify bias due to weak variation. I show that classifying individuals by quantiles and randomizing the type of peer improves precision and bias. I apply this design in a large-scale field experiment at selective public boarding schools in Peru, focusing on social skills. Peer effects are more pronounced for social than academic skills and are heterogeneous by gender and baseline characteristics. While boys assigned to more sociable peers develop higher social skills, drop out less, and enroll at better colleges, more sociable peers do not affect girls' outcomes. Average academic peer effects are a precisely estimated zero, with negative impacts on lower-achieving girls. Gender differences in the formation of students' beliefs about their abilities explain these findings, revealing the role of self-confidence in peer allocation policies.
Choice and Consequence: Assessing Mismatch at Chicago Exam Schools with Joshua Angrist and Parag Pathak. NBER Working Paper 26137.
The educational mismatch hypothesis asserts that students are hurt by affirmative action policies that place them in selective schools for which they wouldn't otherwise qualify. We evaluate mismatch in Chicago's selective public exam schools, which admit students using neighborhood-based diversity criteria as well as test scores. Regression discontinuity estimates for applicants favored by affirmative action indeed show no gains in reading and negative effects of exam school attendance on math scores. But these results are similar for more- and less-selective schools and for applicants unlikely to benefit from affirmative-action, a pattern inconsistent with mismatch. We show that Chicago exam school effects are explained by the schools attended by applicants who are not offered an exam school seat. Specifically, mismatch arises because exam school admission diverts many applicants from high-performing Noble Network charter schools, where they would have done well. Consistent with these findings, exam schools reduce Math scores for applicants applying from charter schools in another large urban district. Exam school applicants' previous achievement, race, and other characteristics that are sometimes said to mediate student-school matching play no role in this story.
Cash and Ballots: Conditional Transfers, Political Participation and Voting Behavior with Emily Conover, Adriana Camacho and Javier Báez. Economic Development and Cultural Change (forthcoming).
Regression Discontinuity in Serial Dictatorship: Achievement Effects at Chicago’s Exam Schools with Atila Abdulkadiroglu, Joshua Angrist, Yusuke Narita, and Parag Pathak. American Economic Review, Papers & Proceedings, 107(5), 240-245.
Work in Progress
The Signaling Value of Elite High Schools: Evidence from Higher Education in Peru with Pía Basurto and Manuel Barrón.
Proximity and Diversity in Network Formation with Arda Gitmez.