The Influence of Classmates on Adolescent Criminal Activities in the United States

ABSTRACT

This article examines the effect of delinquent peers on an individual’s criminal activity by leveraging quasi-experimental variation in exposure to peers, separating confounding and causal effects. In particular, we examine the role of wider peer networks (i.e., classmates) as a critical source of influence on adolescents’ delinquent behavior. Using a combined instrumental variables/fixed effects methodology, we address important methodological challenges in estimating peer effects. Results suggest that increasing the proportion of peers who engage in criminal activities by 5% will increase the likelihood an individual engages in criminal activities by 3 percentage points.

Acknowledgments

We are grateful to Sebastian Daza for useful comments and discussions. This research uses data from Add Health, a program project directed by Kathleen Mullan Harris and designed by J. Richard Udry, Peter S. Bearman, and Kathleen Mullan Harris at the University of North Carolina at Chapel Hill, and funded by grant P01-HD31921 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, with cooperative funding from 23 other federal agencies and foundations. Special acknowledgment is due Ronald R. Rindfuss and Barbara Entwisle for assistance in the original design. Information on how to obtain the Add Health data files is available on the Add Health website (http://www.cpc.unc.edu/addhealth). No direct support was received from grant P01-HD31921 for this analysis.

Funding

This research was supported by a core grant to the Center for Demography and Ecology at the University of Wisconsin–Madison (P2C HD047873).

Supplementary material

Supplementary material for this article can be accessed on the publisher’s website.

Notes

¹ In order to maximize the available sample, single imputation techniques were used to impute family income and maternal education, and a dummy variable reflecting this missingness was included in the estimation models. The following variables were used in the imputation for both variables: age, gender, race/ethnicity, test score, rural status, and parental socioeconomic status (if available).

² We confirm that using the parental incarceration variable only indicating incarcerations before Wave 1 does not affect the findings of this study. The regression coefficient of endogenous peer effects remains almost identical and F-statistic slightly improves (results not shown, but available on request).

³ We find that the results are almost identical and F-statistic slightly weakens when we drop all the observations that do not have Wave 4 information to calculate classmates’ parental incarceration (results not shown, but available on request).

⁴ In order to examine whether the peer effects differ by types of offending, I present the results from separate regression models for each type of criminal activity (Table S5 in supplementary material). The coefficients of peer effects only for burglary and robbery are statistically significant, suggesting that peers might have an impact on certain criminal activities. The reported F-statistic for burglary is modest (6.1) while the over-identification test fails to reject the validity of the instruments. With a 5% increase in the percentage of classmates who have ever committed burglary, the probability that an individual will engage in burglary increases by almost 3.2 percentage points. For armed robbery, the F-statistic (6.5) is similarly modest, and the over-identification tests also indicate that the instruments used are valid. The effect of peers’ involvement in robbery is stronger than burglary, suggesting that a 5% increase in the percentage of classmates who have engaged in armed robbery is associated with the increased probability of individual’s committing robbery by 4 percentage points.

⁵ We use the “plausexog” code by Damian Clarke (2014) downloadable via ssc install plausexog.

⁶ At least 50% and 30% of the reduced form effect of peers’ parental incarceration and co-residence with both biological parents, respectively, must go through channels other than peers’ criminal activity or the estimate of endogenous peer effects to cease to be statistically significant.

Additional information

Funding

This research was supported by a core grant to the Center for Demography and Ecology at the University of Wisconsin–Madison (P2C HD047873).

Notes on contributors

Jinho Kim

JINHO KIM is a Ph.D. candidate in the Department of Sociology at the University of Wisconsin–Madison. The overarching theme of his research is to examine the way in which social context (e.g., peers, family, school, neighborhood) influences the outcomes of young people, primarily in adolescence and at the transition to adulthood. He is particularly motivated by an interest in rigorous research designs for causal inference using non-experimental data.

Jason M. Fletcher

JASON M. FLETCHER is Professor of Public Affairs and Sociology at the University of Wisconsin–Madison. His research interests include estimating the impacts of peers and social networks on education and health behaviors of adolescents. He is affiliated with the Center for Demography and Ecology, Center for Demography of Health and Aging, and Institute for Research on Poverty at the University of Wisconsin–Madison and the National Bureau of Economic Research and Institute for the Study of Labor.