Peer Effects with Random Assignment: Results for Dartmouth Roommates

This paper uses a unique data set to measure peer effects among college age roommates. Freshman year roommates and dormmates are randomly assigned at Dartmouth College. I find that in this group, peer effects are very important in determining levels of academic effort and in decisions to join social groups such as fraternities. Residential peer effects are markedly absent in other major life decisions such as choice of college major. Several forms of peer effects are considered. The data support a model in which peer effects are driven by roommate behavior after the freshmen arrive. Social learning based on a roommate's observable pre-Dartmouth information or skills appears to be less important. Peer effects in GPA occur at the individual room level whereas peer effects in fraternity membership occur both at the room level and the entire dorm level. I also find that a freshman with high social ability is likely to remain with his or her roommates in sophomore year, but high academic ability actually decreases roommate retention.