TABLE 4.
Friendship Network and Past Month Marijuana Use Dynamics: Interaction Between Friend Influence and Friend Popularity
| Model parameter | School 1 |
School 2 |
||||
|---|---|---|---|---|---|---|
| P.E. | SE |
p value |
P.E. | SE |
p value |
|
| Friendship network dynamics | ||||||
| Rate parameter | 8.50 | 0.63 | - | 15.45 | 0.99 | - |
| Effects of network structure | ||||||
| Outdegree | −4.92 | 0.21 | .000 | −3.02 | 0.15 | .000 |
| Reciprocity | 3.13 | 0.13 | .000 | 2.18 | 0.13 | .000 |
| Transitive triplets | 0.70 | 0.07 | .000 | 0.21 | 0.09 | .017 |
| 3-cycles | −1.09 | 0.13 | .000 | −0.12 | 0.16 | .444 |
| Transitive ties | 1.31 | 0.13 | .000 | 1.24 | 0.10 | .000 |
| Outdegree popularity (sqrt) | −0.49 | 0.08 | .000 | −0.29 | 0.08 | .000 |
| Effects of covariates | ||||||
| Gender ego | 0.11 | 0.07 | .100 | 0.04 | 0.06 | .526 |
| Gender alter | 0.03 | 0.06 | .616 | 0.03 | 0.05 | .559 |
| Same gender | 0.33 | 0.05 | .000 | 0.09 | 0.05 | .090 |
| Same race/ethnicity | 1.17 | 0.06 | .000 | - | ||
| Grade ego | −0.14 | 0.07 | .035 | −0.08 | 0.07 | .250 |
| Grade alter | 0.19 | 0.06 | .001 | 0.11 | 0.06 | .078 |
| Same grade | 0.42 | 0.05 | .000 | 0.36 | 0.06 | .000 |
| Parent education ego | −0.07 | 0.03 | .035 | NS | ||
| Parent education alter | 0.08 | 0.03 | .004 | NS | ||
| Parent education sq. alter | 0.01 | 0.03 | .638 | NS | ||
| Similar parent education | 0.20 | 0.11 | .078 | NS | ||
| Rate limited nominations | −0.78 | 0.38 | .042 | −0.25 | 0.48 | .610 |
| Limited nominations ego | 0.25 | 0.20 | .204 | 0.50 | 0.19 | .008 |
| Effects of marijuana use | ||||||
| Marijuana use ego | −0.01 | 0.10 | .905 | 0.09 | 0.06 | .103 |
| Marijuana use alter | −0.27 | 0.65 | .684 | 0.37 | 0.20 | .064 |
| Marijuana use sq. alter | 0.16 | 0.21 | .444 | −0.09 | 0.08 | .267 |
| Similar marijuana use | 1.49 | 0.39 | .000 | 1.04 | 0.29 | .000 |
| Marijuana use dynamics | ||||||
| Rate | 4.30 | 0.48 | - | 3.89 | 0.78 | - |
| Shape effects | ||||||
| Linear shape | −1.68 | 0.11 | .000 | −1.27 | 0.14 | .000 |
| Quadratic shape | 0.38 | 0.03 | .000 | 0.39 | 0.05 | .000 |
| Effects of individual covariates | ||||||
| Male | NS | NS | ||||
| Grade | NS | 0.33 | 0.17 | .048 | ||
| Race/ethnicity | NS | NS | ||||
| Parent education | −0.15 | 0.05 | .004 | NS | ||
| Effect of friends | ||||||
| Friends’ marijuana use(influence) | NS | NS | ||||
| Friends’ marijuanause (influence) * Friend popularity | 0.12 | 0.09 | .189 | 0.15 | 0.07 | .041 |
Note. P.E. = parameter estimate. SE = standard error. NS = not statistically significant. Parameters in bold are significant at the p < .05 level. All control effects were score tested during the forward model specification, and only effects found to be marginally or statistically significant (p < .1) were retained and estimated in the models. Effects listed as non-significant were found to be non-significant predictors in this forward selection process and so were not estimated in the final model.