DeLay, Dawn

This study was designed to investigate friend influence on academic
achievement and task avoidance during middle childhood in a sample of 794
participants in 397 stable same-sex friendship dyads (205 girl dyads and 192 boy dyads)
from four municipalities in Finland: two in Central Finland, one in Western Finland,
and one in Eastern Finland. Longitudinal data were collected during the spring of 3rd
grade and 4th grade and reports were available from both members of each friendship
dyad. The Actor-Partner Interdependence Model (APIM; Kenny, Kashy & Cook, 2006)
was used with a single sample of participants to estimate friend influence on academic
achievement and task avoidance between two types of friendship dyads: (1) dyads that
were distinguishable as a function of relative math achievement and relative peer
acceptance and (2) dyads that were indistinguishable as a function of relative math
achievement and relative peer acceptance. The results demonstrate that when friends are distinguished by math achievement the high achiever influences the low achiever’s math achievement, but not the reverse. When friends are distinguishable by peer acceptance the high accepted partner influences the low accepted partner’s math achievement, but not the reverse. When friends are indistinguishable on the basis of math achievement and peer
acceptance there is mutual influence on math achievement. There was no evidence of
friend influence on task avoidance. There was no evidence of friend influence from an
individual’s own task avoidance predicting changes in friend math achievement, except
among dyads that could not be distinguished on the basis of math achievement. Math
achievement predicted within-individual changes in task avoidance for all friendship
dyads, except those that could not be distinguished by relative math achievement.
The findings suggest that friends influence math achievement during middle
childhood. Furthermore, when friends are distinguished, relative math achievement and
peer acceptance determines who is influencing whom within a friendship dyad. The use
of the APIM for distinguishable and indistinguishable dyads on a single sample of
participants illustrates that it is not sufficient to ignore differentiating features between
friends, or to discard friendships that are more similar. Implications for teaching
strategies and classroom interventions are discussed.

Friends have been implicated in the acquisition of adolescent substance use, but little attention has been given to how the origins of substance use similarity vary across groups. The first aim of this study is to examine whether friend selection, de-selection, and socialization differ as a function of friendship group's substance use. The second aim of this study is to extend Simulation Investigation for Empirical Network Analyses (SIENA) by demonstrating how group-level interactions can be included in the mode, and to demonstrate a new method to follow-up statistically significant group-level interactions in SIENA. Participants include 1419 Finnish students (729 females, 690 males) from upper secondary schools in Finland. Two waves of data were collected, starting when most participants were between 15 and 17 years of age. Waves of data collection were separated by one year. Results indicate that friends are selected, deselected, and socialized for substance use. Follow-up illustrations indicate that the magnitude of these processes vary as a function of substance use in the friendship group.