Peer Effects and Alcohol Use among College Students

The study uses a natural experiment instead of intentional intervention as it looks at how randomly assigned roommates affect the cumulative GPA of first and second year students. The study takes advantage of a random housing lottery and the Cooperative Institutional Research Program's (CIRP's) Entering Student Survey, which contains data on a rich set of student characteristics prior to college entrance, from a large state university to examine the impact of peers' nonacademic characteristics--alcohol consumption in particular.

1997-08-01

1999-08-31

Cumulative grade point average.

No outcomes were constructed as all data was directly (but anonymously) reported.

The study uses a sub-set of the incoming class of 7,500 students starting their freshman year in 1997 and 1998 that entered the housing lottery. A subset of these students (those who chose not to live in an 'enrichment center' and who met the housing lottery deadline) were randomly assigned to rooms (and roommates). This left a sample of 1,357 students. These students put in preferences for (i) gender (ii) substance or smoking free (iii) number of roommates (iv) geographical area on campus. Random assignment was conditional on these preferences, and hence all regression specifications control for these preferences. An analysis done for a second group of students who requested their roommates was used to assess how large the selection bias problem would have been for a non-experimental study.

The primary outcome of interest was the cumulative GPA for all students at the end of summer of 1999. This would represent the freshman-year grades for one group in the sample, and sophomore- year grades for the rest. Thus for the latter group, the study also looks at continuing effect of the first-year roommate since in the second year only 17% choose to continue living with the same person.

Explanatory variables related to roommate drinking were obtained from the Entering Student Survey of the Cooperative Institutional Research Program (CIRP) which was administered to all admitted students during their orientation week in the summer prior to starting classes and had a response rate of 89%. This survey contains a section in which respondents are presented with a list of activities and asked whether they undertook the activities frequently, occasionally, or not at all during the last year. The list of activities includes "Drank beer" and "Drank wine or liquor." Respondents who answered "frequently" to at least one of the two drinking-related questions were classified as "frequent drinkers". Respondents who were not "frequent drinkers" but answered "occasionally" to at least one of the two drinking related questions were classified as "occasional drinkers". Students who reported not drinking beer, wine, or liquor in the last year were classified as "nondrinkers."

Computer

Students

No

No cluster;
1,357 STUDENTS

1,357 STUDENTS

650 TREATMENT and 707 CONTROL

PEER EFFECTS AND ALCOHOL USE AMONG COLLEGE STUDENTS

This paper examines a natural experiment in which students at a large state university were randomly assigned roommates through a lottery system. We find that on average, males assigned to roommates who reported drinking in the year prior to entering college had one quarter-point lower GPA than those assigned to non-drinking roommates. The 10th percentile of their college GPA is half a point lower than among males assigned non-drinking roommates. For males who themselves drank frequently prior to college, assignment to a roommate who drank frequently prior to college reduces GPA by two-thirds of a point. Since students who drink frequently are particularly influenced by frequent-drinking roommates, substance-free housing programs could potentially lower average GPA by segregating drinkers. The effect of initial assignment to a drinking roommate persists and possibly even grows over time. In contrast, students' college GPA is not influenced by roommates' high school grades, admission test scores, or family background. Females' GPAs are not affected by roommates' drinking prior to college. Overall, these findings are more consistent with models in which peers change preferences than models in which they change endowments.

Kremer, Michael, and Dan Levy. 2008. "Peer Effects and Alcohol Use Among College Students." Journal of Economic Perspectives 22(3): 189-206.

https://www.povertyactionlab.org/sites/default/files/publications/28%20peer%20effects%202008.pdf