Peer Effects in Academic Outcomes: Evidence From a Natural Experiment

In this paper I use data from Williams College to implement a quasi-experimental empirical strategy aimed at measuring peer effects in academic outcomes. In particular, I use data on individual student's grades, SAT scores, and the SAT scores of their roommates. I argue that first year roommates are assigned randomly with respect to academic ability. This allows me to measure differences in grades of high, medium, or low SAT students living with high, medium or low SAT roommates. With random assignment these estimates would provide compelling estimates of the effect of roommates' academic characteristics on an individual's grades. I also consider the effect of peers at somewhat more aggregated levels. In particular, I consider the effects associated with different "academic environments" in clusters of rooms that define distinct social units. The results suggest that peer effects are almost always linked more strongly with verbal SAT scores than math SAT scores. Students in the middle of the SAT distribution may do somewhat worse in terms of grades if they share a room with a student who is in the bottom 15 percent of the verbal SAT distribution. Students in the top of the SAT distribution are least affected by the SAT scores of their (room or entry) peers. The effects are not large, but are statistically significant in many models.