Table 1.

Review of recent studies of peer socialization and selection on adolescent smoking^*§

Author and Year	Sample and Location	Adolescent Use Measure (Outcome)	Peer Use Measure	Assessment	Analyses	Significant Findings	Conclusion
Latent Growth Model, General Linear Equation, Structural Equation Modeling
Wills, Cleary, 1999	1190 7th graders The US; New York metropolitan area	Frequency of use of tobacco, alcohol or marijuana (composite measure) Having more than three drinks on one occasion in the past month	Number of friends who smoke cigarettes, drink beer or wine, smoke marijuana	Respondents Questionnaires at three time points (3-year follow-up) Peers Respondents’ reports at all three time points	Analyze peer-influence vs. peer selection mechanisms in adolescent tobacco, alcohol and marijuana use Analysis strategy Latent growth modeling; multiple regression	Peer smoking associated with change in adolescent smoking Adolescent smoking did not increase friends who smoke	Evidence of socialization No evidence of selection
De Vries,	15705 adolescents; mean age = 13.6 Six European countries: Denmark, Finland, The Netherlands, Portugal, Spain, UK	Never smokers Tried, but not regular smokers; Regular smokers: smoking at least once a week.	A three-point scale for best friend (yes, maybe, no). A five-point scale for friends in general (all, more than half, half, less than half, hardly anybody).	Respondents Questionnaires at two time points Peers Participants’ report of their friends’ smoking at two time points	Assess the relationship between smoking behaviors of adolescents and smoking status of their parents and friends. Analysis strategy Multiple regression analyses	Longitudinal regression analysis showed that the β coefficients of the smoking status of the best friend and friends in general were comparable to that of parental smoking.	No evidence of socialization Evidence of selection
Simons-Morton, Chen, Abroms, Haynie, 2004	1320 6th graders The US; Maryland	Frequency of smoking in the past 30 days and past 12 months	Number of five closest friends who smoke Number of five closest friends who drink, cheat on a test, bully someone, act disrespectfully, steal, lie to parents, damage property	Respondents Questionnaires at five time points (3-year follow-up) Peers Respondents’ reports at all time points	Examine associations between initial and continuing peer affiliation and parent influences and smoking stage progression Analysis strategy latent growth curve; lagged autoregressive latent trajectory analyses	Consistency between adolescents and peers in smoking at baseline and over time. Protective effect of authoritative parenting practices on the formation of friends who smoke	No evidence of socialization Evidence of selection
Audrain-McGovern, Rodriguez, Tercyak, Neuner, Moss, 2005	918 9th graders The US; Northern Virginia	Variable measuring smoking progression that includes: never smokers, puffers, experimenters, current smokers and frequent smokers	Composite measuring smoking among nine best friends: Best friend smoking Number of other 4 best male and best female friends who smoke	Respondents Questionnaires at 5 time points (4-year follow-up) Peers Respondents’ reports at 4 time points	Determine whether self-control had indirect effects on smoking practices through effects on peer smoking Analysis strategy Latent curve growth modeling	Evidence that peer smoking directly influences adolescent smoking progression Problems with impulse control increased likelihood of having peer who smokes, indirectly increasing smoking likelihood at baseline; opposite effect for increased planning	Evidence of socialization Indirect effect of selection
De Vries, Candel, Engels, Mercken, 2006	7102 adolescents; mean age of 12.78 years Six European countries: Finland, Denmark, the Netherlands, the United Kingdom, Spain and Portugal	Weekly smoking	Best friend ever smoking Number of friends who smoke	Respondents Questionnaires at two time points (1-year interval) Peers Adolescents’ reports of their friends’ smoking at two time points	Examine the influence of friends’ smoking at Times 1 and 2 on respondents’ smoking at Time 2 Analysis strategy Structural Equation Modeling	No association between friends’ smoking at T1 and adolescent smoking at T2 for most countries. Significant positive association between adolescent smoking at T1 and friends’ smoking at T2	No evidence for socialization Evidence of selection
Mercken, Candel, Willems, DeVries, 2007	1886 adolescents; mean age of 12.7 years. The Netherlands	Average # cigarettes smoked during week	Average # cigarettes smoked during week	Respondents Questionnaires at two time points (1 year interval) Peers Self-reported smoking of five best friends attending the same school at two time points	Examine the influence of friends’ smoking at Times 1 and 2 on respondents’ smoking at Time 2 Analysis strategy Structural Equation Modeling	Within non-reciprocal friendships, effect of social selection Within reciprocal friendships, effect of socialization and to a lesser extent, social selection	Evidence of socialization Evidence of selection
Hoffman, Monge, Chou, Valente, 2007	20,747 participants in Add Health 7th– 12th grade The US; National	Ever tried smoking	Number of friends who smoke at least one cigarette a day, out of three best friends	Respondents Questionnaires at two time points (1-year follow-up) Peers Respondents’ reports at both time points	Test a model of peer influence and peer selection on ever smoking by adolescents Analysis strategy Structural equation modeling	Smoking at Time 1 was more strongly associated with peer smoking at Time 2 than Time 1 peer smoking with Time 2 adolescent smoking	No evidence of socialization Evidence of selection
Auto-regressive analyses
Simons-Morton, Chen, 2006	2453 6th graders The US; Maryland	Frequency of smoking, drinking, marijuana use past 30 days (composite measure)	Number of five closest friends who smoke, drink, or use marijuana	Respondents Questionnaires at five time points (3-year follow-up) Peers Respondents’ reports at all time points	Examine reciprocal influence of adolescent and peer substance use from one time point to the next Analysis strategy lagged autoregressive latent trajectory analyses	Great consistency between adolescents and peers in substance use over time. Evidence of reciprocal effects of peer use leading to adolescent use and adolescent use leading to peer use.	Socialization was a less consistent predictor than selection
Tucker, Martinez, Ellickson, Edelen, 2008	6527 7th graders The US; Oregon	Composite measuring quantity and frequency of smoking	Best friend smoking Frequency the participant is around kids who are smoking cigarettes	Respondents Questionnaires at four time points (10-year follow-up) Peers Respondents’ reports at all time points	Investigate the temporal associations of adolescent smoking with pro- smoking family and peer influences Analysis strategy Path analyses of cross- lagged effects	Stronger effect of youth smoking on friendship formation than the reverse Household smoking and parent approval predicted smoking, while parent disapproval was negatively associated with future smoking and friendships with smokers	Reciprocal influences Socialization effects less consistent over time than selection effects
Social Network Analyses
Maxwell, 19 2002	69 adolescents, aged 12–18 The US; national sample	Current smoking, marijuana use and chewing tobacco (30past days) (separate outcomes) Current drinking (past 12 months)	Current smoking, marijuana use and chewing tobacco (past 30 days) Current drinking (past 12 months)	Respondents Questionnaires at two time points (1-year follow-up) Peers Self-reported at both time points (one same- sex friend per participant, among all nominated friends)	Examine peer influence across five risk behaviors: cigarette smoking, alcohol consumption, marijuana use, tobacco chewing, and sexual debut Analysis strategy Logistic regression	Random same sex peer behavior predicted teen smoking and marijuana initiation and alcohol initiation and discontinuation Friends protect against risk activities as well as promote initiation	Evidence of socialization Did not measure selection
Urberg, Luo, Pilgrim, Degirmencioglu, 2003	1028 6th, 8th and 10th grade (some attrition for future waves) The US, Midwest	Ever use of cigarettes or alcohol (separate outcomes) Current use of cigarettes or alcohol Frequency of drunkenness in the past month	Same as adolescent use measures. Computed for best friends and other friends	Respondents Questionnaire at 4 time points (3-year follow- up) Peers Friends’ reports at all time points	Assess (1) the initial selection of cigarette- and alcohol using peers and (2) influence from peers Analysis strategy Hierarchical regressions	Adolescents with low school achievement value or little time with parents more likely to choose friends who smoked High peer acceptance and high friendship quality associated with greater adolescent conformity to friend’s substance-use	Evidence of socialization Evidence of selection
Kirke, 2004	267 adolescents, aged 14-18 Ireland	Ever use of cigarettes, alcohol and drugs (separate outcomes )	Ever use of cigarettes, alcohol and drugs	Respondents Questionnaire at one time point (use information about when the friendship was formed) Peers Self-reported from nominated friends	Examine relative impact of peer influence and selection on similarity in the substance use Analysis strategy Social network analysis	Similarity in the substance use of adolescents is due to both peer socialization influence and selection Greater role of peer influence.	Evidence of socialization Evidence of selection
Hall, Valente, 2007	1960 6th graders Location not specified	Ever trying smoking, even a few puffs	Ever trying smoking, even a few puffs	Respondents Questionnaires at three time points (1-year follow-up) Peers Self-reported at all time points (from 5 best friends)	Examine the processes of peer socialization and selection on adolescent smoking Analysis strategy Social network analysis	Nominating smokers as friends predicted future smoking Being nominated as a friend provided indirect influence on future smoking	Evidence of indirect effect of socialization Evidence of selection

^*Some of the studies have included other risk behaviors (generally other substance use), in addition to smoking

^§All of the included studies are longitudinal except for Kirke, 2004; but this study was included because of its importance in addressing the socialization/selection paradigm