Peer Effects, Alcohol and College RoommatesPDF version
Alcohol abuse causes an estimated 85,000 deaths per year in the United States. It is a particularly salient issue at colleges and universities. Many campaigns in colleges aimed at reducing alcohol abuse are based on the premise that informing students that their peers drink less than they think will in turn lead them to drink less. The importance of peer effects in drinking behavior is also central to recent debates concerning substance-free dorms as well as online roommate matching systems. It is therefore important to assess the role that peer effects play in student drinking behaviors and habits. Many studies argue that substance abuse is subject to substantial peer effects, based on observations of a positive association between teenagers’ substance use and substance use among their peers. However, it is often difficult to empirically determine whether a correlation between peers’ outcomes is due to peer effects, to self-selection of similar peers, or to common shocks affecting the peer group.
College universities are a natural place to examine the formation of preferences through forces such as peer influences and habit formation. Students are separated from parents and many of their previous peers, and have an opportunity to “choose” a new identity. College is also an important locus of substance abuse, with 40 percent of students reporting binge drinking at least once within the past two weeks. After tobacco, alcohol is the most frequently abused drug in the United States, and many addictions develop in college. Most health professionals agree that alcohol affects practically every organ in the human body and consumption is linked to more than 60 disease conditions. Depending on the level of consumption and when it begins in life, the social and health related results of alcohol addictions can significantly impede educational attainment, job performance, and quality of life.
This study examines a natural experiment in which students at a large state university were randomly assigned roommates through a lottery system. Students at this university had performed well in high school, achieving an average aptitude test score of around the 90th percentile of the national average. While the population had slightly above average student alcohol consumption, the university was never listed as a top twenty party school.
A set of 1,357 first year students were assigned roommates randomly, and a second set, who had requested their roommate specifically, was used for comparison. Entering students completed a survey which asked whether they undertook certain activities such as alcohol use, and a second survey was completed later that school year.
While females’ grade point averages (GPAs) were not affected by their roommate’s drinking prior to college, on average, males assigned to roommates who reported drinking in the year prior to entering college had a one quarter-point lower GPA than those assigned to non-drinking roommates. Roommates’ drinking greatly reduced the lower tail of the GPA distribution, somewhat decreased the median GPA, and had a small negative impact on the upper tail of GPA distribution. Among males, having a roommate who drinks occasionally reduces the lower 10th percentile of GPA by a half a point. For males who themselves drank prior to college, assignment to a roommate who drank frequently prior to college reduced GPA even more significantly, by two-thirds of a point.
The effect of an initial assignment to a drinking roommate persists and possibly even grows over time, revealing much about preference formation and subsequent future behavior in this case. Since students who drink frequently are particularly influenced by frequent-drinking roommates, substance-free housing programs could potentially lower average GPA across the student body by segregating drinkers and reinforcing their behavior.
