Peer Effects and Alcohol Use among College Students
Last registered on January 05, 2017

Pre-Trial

Trial Information
General Information
Title
Peer Effects and Alcohol Use among College Students
RCT ID
AEARCTR-0001062
Initial registration date
January 05, 2017
Last updated
January 05, 2017 10:31 AM EST
Location(s)
Primary Investigator
Affiliation
Harvard Kennedy School, Harvard University
Other Primary Investigator(s)
PI Affiliation
Department of Economics,Harvard University, Cambridge, Massachusetts
Additional Trial Information
Status
Completed
Start date
1997-08-01
End date
2003-07-31
Secondary IDs
Abstract
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.
External Link(s)
Registration Citation
Citation
Kremer, Michael and Dan Levy. 2017. "Peer Effects and Alcohol Use among College Students." AEA RCT Registry. January 05. https://doi.org/10.1257/rct.1062-1.0.
Former Citation
Kremer, Michael, Dan Levy and Dan Levy. 2017. "Peer Effects and Alcohol Use among College Students." AEA RCT Registry. January 05. http://www.socialscienceregistry.org/trials/1062/history/12905.
Sponsors & Partners

There are documents in this trial unavailable to the public. Use the button below to request access to this information.

Request Information
Experimental Details
Interventions
Intervention(s)
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.
Intervention Start Date
1997-08-01
Intervention End Date
1999-08-31
Primary Outcomes
Primary Outcomes (end points)
Cumulative grade point average.
Primary Outcomes (explanation)
No outcomes were constructed as all data was directly (but anonymously) reported.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
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."
Experimental Design Details
Randomization Method
Computer
Randomization Unit
Students
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
No cluster;
1,357 STUDENTS
Sample size: planned number of observations
1,357 STUDENTS
Sample size (or number of clusters) by treatment arms
650 TREATMENT and 707 CONTROL
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
Study has received IRB approval. Details not available.
IRB Approval Date
Details not available
IRB Approval Number
Details not available
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
Yes
Intervention Completion Date
August 31, 1999, 12:00 AM +00:00
Is data collection complete?
Yes
Data Collection Completion Date
March 31, 2000, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
No cluster;
1,357 STUDENTS
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
1,357 STUDENTS
Final Sample Size (or Number of Clusters) by Treatment Arms
N/A
Data Publication
Data Publication
Is public data available?
No
Program Files
Program Files
No
Reports and Papers
Preliminary Reports
Relevant Papers
Abstract
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.
Citation
Kremer, Michael, and Dan Levy. 2008. "Peer Effects and Alcohol Use Among College Students." Journal of Economic Perspectives 22(3): 189-206.