Peer effects with random assignment: Results for Dartmouth roommates

This paper uses a unique data set to measure peer effects among college roo mmates. Freshman year roommates and dormmates are randomly assigned at Dart mouth College. I find that peers have an impact on grade point average and on decisions to join social groups such as fraternities. Residential peer e ffects are markedly absent in other major life decisions such as choice of college major. Peer effects in GPA occur at the individual room level, wher eas peer effects in fraternity membership occur both at the room level and the entire dorm level. Overall, the data provide strong evidence for the ex istence of peer effects in student outcomes.