the frequency of substance use, (b) a SAAF–T × DRD4 interaction effect on increases in protective parenting, (c) a link between increases in protective parenting and decreases in youths’ substance use, and (d) a nonsignificant SAAF–T × DRD4 interaction effect on youth substance use when the SAAF–T × DRD4 interaction effect on increases in protective parenting was included in the model. A negative binomial model was used in this second step because it allows for overdispersion in the substance use outcome measure. Figures 2 and 3 present the results from the SEM analysis that tests the SAAF–T × DRD4 interaction for intervention-targeted protective parenting and the mediated moderation hypothesis, respectively. The Wald test (Wald, 1947) was used to test the hypothesized indirect effect, and all models were analyzed with Mplus 6.11 (Muthén & Muthén, 1998–2010).
