Social scientists continue to devote considerable attention to spillover effects for risky behaviors because of the important policy implications and the persistent challenges in identifying unbiased causal effects. We use the natural experiment of assigned college roommates to estimate peer effects for several measures of health risks: binge drinking, smoking, illicit drug use, gambling, having multiple sex partners, suicidal ideation, and non-suicidal self-injury. We find significant peer effects for binge drinking but little evidence of effects for other outcomes, although there is tentative evidence that peer effects for smoking may be positive among men and negative among women. In contrast to prior research, the peer effects for binge drinking are significant for all subgroups defined by sex and prior drinking status. We also find that pre-existing risky behaviors predict the closeness of friendships, which underscores the significance of addressing selection biases in studies of peer effects.
Bibliographical noteFunding Information:
Funding from the W.T. Grant Foundation and from the National Institute for Child Health and Human Development ( 5R24HD041023 ) is gratefully acknowledged. We received helpful comments from many people including: Martha Bailey; Jason Fletcher; Adriana Lleras-Muney; Amanda Purington; Ed Seidman; Stephanie von Hinke Kessler Scholder; and seminar participants at the University of Michigan, UC-Berkeley, and the 2011 NBER Health Summer Institute. Much of this work was conducted while Ezra Golberstein was an NIMH Research Fellow at the Department of Health Care Policy at Harvard Medical School. The survey data collection was coordinated by Scott Crawford, Sara O’Brien, and their colleagues at the Survey Sciences Group, LLC. We are also grateful to the university staff members who helped us obtain administrative data and to the students who participated in the surveys.
- Peer effects
- Risky behaviors
- Substance use