Identifying Peer Effects in Substance Abuse Treatment
- Presenter:
Chair: Catherine McLaughlin; Discussant: Phil DeCicca Mon June 5, 2006 13:45-15:15 Room 225
Background: A wide variety of studies have examined the impact of peers on outcomes including education, crime, health, and labor market activity. Peer effects in drug and alcohol use (particularly among teens) have received considerable academic attention because peers are often thought to be important both for usage and abstinence. Research to date has not adequately isolated causal effects due to the fact that observed peers are typically not randomly assigned but chosen by the individuals studied.
Aims of Study: This study examines the impact of peers in drug and alcohol treatment programs in Connecticut on a variety of outcomes including successful completion of the program, drug usage during and after the program, relapse into drug or alcohol treatment (e.g., future admission for detoxification), crime, and labor market activity. We study the impact of a large set of peer characteristics related to demographic characteristics, past drug usage (by intensity and drug category), criminal activity, and labor market activity on these outcomes.
Methods: Using data from all drug treatment facilities in Connecticut, we use the methodology developed in Bayer et. al. (2004) to isolate causal effects of peers on outcomes. This methodology uses only the within-program variation in peer characteristics and therefore eliminates any variation associated with the selection or assignment into particular facilities. Because individuals spend reasonably short amounts of time in treatment and are admitted and released from programs on a regular basis, considerable variation exists in the characteristics of one’s peers in terms of past drug use, criminal activity, labor market activity, and age depending on the exact period of time that individuals receive treatment.
Results: To date, we have explored the features of the institutional setting in Connecticut. Our primary sample consists of all admissions for drug treatment (over 150,000) in Connecticut from 1995-2003. Of these about 60 percent are outpatient, 15 percent residential-short term, 15 percent residential long-term, and 10 percent methadone maintenance. Individuals were treated in a total of approximately 200 programs over this period. The data reveals a great deal of variation both across and within facilities for the wide set of peer characteristics and outcomes mentioned above, making the institutional setting appropriate for our methodology.
Discussion: This analysis provides a wide set of results that characterize a number of causal channels through which peers affect outcomes. Consequently this study has a number of important implications for how individuals should best be assigned to programs and groups within programs while receiving drug treatment. Additionally, this study informs our understanding of the nature of peer effects in drug use and treatment. The size of these effects have far-reaching policy implications ranging from the optimal timing of drug interventions, to the optimal range of treatment options, to the identification of individuals particularly at risk of relapse.
