Social and Cognitive Peer Effects: Experimental Evidence from Selective High Schools in Peru

A growing literature emphasizes the importance of social skills in the labor market. However, to date, no study addresses the role of peer characteristics in the formation of social skills. This paper reports estimates of cognitive and social peer effects from a large-scale field experiment at selective boarding schools in Peru. My experimental design overcomes some methodological challenges in the peer effects literature. I randomly varied the characteristics of neighbors in dormitories with two treatments: (a) less or more sociable peers (identified by their position in the school’s friendship network before the intervention) and (b) loweror higher-achieving peers (identified by admission test scores). While more sociable peers enhance the formation of social skills, higher-achieving peers do not improve academic achievement; in fact, they further reduce the academic performance of lower-achieving students. These results appear to be driven by students’ self-confidence and the social support they receive from their neighbors. I interpret these findings in the context of a simple self-confidence model where students infer their skills by interacting with their peers. ∗Department of Economics, MIT. Email: razarate@mit.edu. I am deeply grateful to my advisors Joshua Angrist, Esther Duflo, and Parag Pathak for their guidance throughout this project. I also thank Daron Acemoglu, Abhijit Banerjee, and Frank Schilbach for their helpful suggestions. This paper would not have been possible without the support of the staff of the Ministry Education of Peru; I especially thank Marı́a Antonieta Alva and Cinthia Wicht for their collaboration and support, and Paola Encalada for her dedicated work at different stages of this project. I also thank Andrei Bartra, Pı́a Basurto, Antonio Campos, José Carlos Chávez, Yessenia Collahua, Gerald Eliers, Fiorella Guevara, Diego Jara, Ricardo Montero, Raul Panduro, Barbara Sparrow, Guillermo Trefolgi, and Paola Ubillus for their help. I am also grateful to all the directors of the COAR Network for their work during the implementation. Heather McCurdy provided generous help with MIT Institutional Review Board (IRB) documentation. I am particularly grateful to Sydnee Caldwell, Joaquı́n Klot, Matt Lowe, and Francine Loza for their feedback. Claudia Allende, Zach Brown, Alonso Bucarey, Adriana Camacho, Lorena Caro, Nicolás de Roux, Josh Dean, Juan Dubra, Leopoldo Fergusson, David Figlio, Chishio Furukawa, Isabel Hincapie, Nicolás Idrobo, Juán Galán, Arda Gitmez, Gabriel Kreindler, Stephanie Majerowicz, Santiago Melo, Mateo Montenegro, Andrés Moya, Alan Olivi, Gautam Rao, Cory Smith, Vira Semenova, Román David Zárate, David Zarruk, and the participants at the Development, Labor, Organizational lunches at MIT, NEUDC 2018, and the 2018 NAEd/Spencer fellows retreat also provided useful comments and suggestions. Jorge Alva and Marı́a Antonieta Luperdi were very generous during my stay in Peru. This project is part of the MineduLab. Funding for this project was generously provided by the Weiss Family Fund and the NAEd/Spencer dissertation fellowship. The experiment was approved by the MIT IRB (ID 1702862092), and is registered at the AEA RCT Registry (ID 0002600).