Diffusion of Intervention Effects from Peer Leaders to Friends: Effects from Above the Influence

• In Event: 3-043 - From Making to Influencing Friends: Using Social Network Analysis to Guide, Deliver, and Evaluate Peer Interventions

Integrative Statement

Peer-led interventions are often more effective than teacher-led interventions. These improved outcomes may occur as peer opinion leaders adopt the attitudes and behaviors promoted by the intervention and then influence their friends, thus facilitating the diffusion of intervention effects from peer leaders to the broader student population. We use social network analysis to examine diffusion of effects from a school-based peer-led intervention.

We first explored whether non-peer leaders were reached by the intervention and identified factors related to reach. We then tested whether there was evidence of diffusion. We hypothesized that students who had more peer leader friends would express lower substance use intentions at the end of the 5-month intervention period.

Participants were 8th graders at 4 rural middle schools. Each school implemented a peer-led intervention that was developed to integrate with the online Above the Influence social media program. We focus on n = 527 students who were not trained as peer leaders (43% Female; 93% White, 4% Latino, 3% Other).

Researchers invited all 8thgraders to complete an online survey in January (pretest) and May (posttest). After the pretest survey, researchers trained 68 students to lead a school-wide anti-substance use campaign to decrease perceived social rewards of substance use, increase accurate social norming, and increase efficacy to overcome perceived negative social influences. On each survey, students named up to 7 friends, which we used to calculate reach (i.e., whether a student was 1, 2, or 3+ steps from a peer leader) as well as total and proportion of peer leader friends. Students also reported their substance use intentions.

At baseline, 40% of non-peer leaders named a peer leader as a friend and an additional 25% named someone who was friends with a peer leader. Reach varied significantly across schools (χ2 = 43.05, p < .001): Reach was greater in schools where a higher proportion of students were trained as peer leaders. Notably, however, reach was unrelated to baseline intentions (χ2 = 4.40, p = .354): Low- and high-risk students were equally likely to be friends with peer leaders. Substance use intentions did not vary as a function of number of peer leader friends at pretest, but at post-test, students with more peer leader friends reported fewer substance use intentions (Figure 1), providing preliminary evidence of diffusion. Regression analyses, using multiple imputations to account for missing data, indicated that students with a lower proportion of peer leader friends reported higher substance use intentions at posttest (β = -1.42, p = .03), after controlling for baseline intentions and number of intervention activities completed. Figure 2 illustrates what diffusion looks like in one of the four schools. We will also test differential effects across substances, whether diffusion occurs for other intervention outcomes (e.g., social norms), and whether there is an interaction between direct exposure and proportion of peer leader friends.

To facilitate the diffusion of intervention effects, peer-led interventions should focus on maximizing peer leader reach to the student population.

Authors

• Kelly L Rulison, University of North Carolina at Greensboro
  Presenting Author

• Peter A Wyman, University of Rochester
  Non-Presenting Author

• Brandon N Mendenhall, University of North Carolina at Greensboro
  Non-Presenting Author

• Anthony R Pisani, University of Rochester
  Non-Presenting Author