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What Is a Peer? The Role of Network Definitions in Estimation of Endogenous Peer Effects


  • Halliday, Timothy J.

    () (University of Hawaii at Manoa)

  • Kwak, Sally

    () (University of Hawaii at Manoa)


We employ a standard identification strategy from the peer effects literature to investigate the importance of network definitions in estimation of endogenous peer effects. We use detailed information on friends in the Adolescent Longitudinal Health Survey (Add Health) to construct two network definitions that are less ad hoc than the school-grade cohorts commonly used in the educational peer effects literature. We demonstrate that accurate definitions of the peer network seriously impact estimation of peer effects. In particular, we show that peer effects estimates on educational achievement, smoking, sexual behavior, and drinking are substantially larger with our more detailed measures than with the school-grade cohorts. These results highlight the need to further understand how friendships form in order to fully understand implications for policy that alters the peer group mix at the classroom or cohort level.

Suggested Citation

  • Halliday, Timothy J. & Kwak, Sally, 2008. "What Is a Peer? The Role of Network Definitions in Estimation of Endogenous Peer Effects," IZA Discussion Papers 3335, Institute for the Study of Labor (IZA).
  • Handle: RePEc:iza:izadps:dp3335

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    Cited by:

    1. Ajilore, Olugbenga & Amialchuk, Aliaksandr & Egan, Keven, 2016. "Alcohol consumption by youth: Peers, parents, or prices?," Economics & Human Biology, Elsevier, vol. 23(C), pages 76-83.
    2. Stephen L. Ross, 2009. "Social Interactions within Cities: Neighborhood Environments and Peer Relationships," Working papers 2009-31, University of Connecticut, Department of Economics.
    3. repec:taf:vjerxx:v:109:y:2016:i:1:p:37-49 is not listed on IDEAS
    4. Son Thierry Ly & Arnaud Riegert, 2014. "Persistent Classmates: How Familiarity with Peers Protects from Disruptive School Transitions," PSE Working Papers halshs-00842265, HAL.
    5. Loh, Chung-Ping A. & Li, Qiang, 2013. "Peer effects in adolescent bodyweight: Evidence from rural China," Social Science & Medicine, Elsevier, vol. 86(C), pages 35-44.
    6. Bet Caeyers, 2014. "Exclusion bias in empirical social interaction models: causes, consequences and solutions," CSAE Working Paper Series 2014-05, Centre for the Study of African Economies, University of Oxford.
    7. BARONE, Adriana & NESE, Annamaria, 2014. "Body Weight and Academic Performance: Gender and Peer Effects," CELPE Discussion Papers 129, CELPE - Centre of Labour Economics and Economic Policy, University of Salerno, Italy.
    8. repec:bpj:bejeap:v:17:y:2017:i:3:p:10:n:9 is not listed on IDEAS
    9. Asirvatham, Jebaraj & Nayga, Rodolfo M., Jr. & Thomsen, Michael R., 2012. "Peer-Effects In Obesity Among Public School Children: A Grade-Level Analysis," 2012 AAEA/EAAE Food Environment Symposium, May 30-31, Boston, MA 122732, Agricultural and Applied Economics Association.
    10. Olugbenga Ajilore, 2015. "Identifying peer effects using spatial analysis: the role of peers on risky sexual behavior," Review of Economics of the Household, Springer, vol. 13(3), pages 635-652, September.
    11. Kiss David, 2017. "A Model about the Impact of Ability Grouping on Student Achievement," The B.E. Journal of Economic Analysis & Policy, De Gruyter, vol. 17(3), pages 1-10, July.
    12. Moriarty, John & McVicar, Duncan & Higgins, Kathryn, 2016. "Cross-section and panel estimates of peer effects in early adolescent cannabis use: With a little help from my ‘friends once removed’," Social Science & Medicine, Elsevier, vol. 163(C), pages 37-44.
    13. Bet Caeyers & Marcel Fafchamps, 2016. "Exclusion Bias in the Estimation of Peer Effects," NBER Working Papers 22565, National Bureau of Economic Research, Inc.
    14. Josep-Oriol Escardíbul & Toni Mora & Anna Villarroya, 2013. "Peer effects on youth screen media consumption in Catalonia (Spain)," Journal of Cultural Economics, Springer;The Association for Cultural Economics International, vol. 37(2), pages 185-201, May.
    15. Halliday, Timothy J. & Kwak, Sally, 2009. "Weight gain in adolescents and their peers," Economics & Human Biology, Elsevier, vol. 7(2), pages 181-190, July.
    16. Trogdon, Justin G. & Allaire, Benjamin T., 2014. "The effect of friend selection on social influences in obesity," Economics & Human Biology, Elsevier, vol. 15(C), pages 153-164.
    17. repec:oxf:wpaper:wps/2014-05 is not listed on IDEAS

    More about this item


    education; adolescent health; peer effects;

    JEL classification:

    • I12 - Health, Education, and Welfare - - Health - - - Health Behavior
    • I20 - Health, Education, and Welfare - - Education - - - General

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