A separate set of analyses examined the effect of average parental knowledge on the intercept and slope of adolescents’ substance use. Parental knowledge was significantly associated with a decreased likelihood of adolescent substance use at the intercept (with odds ratios ranging from .78 to .84). Across all substances, every one-unit increase in parental knowledge was associated with a substance use decrease ranging from 16 to 22 percent. However, average parental knowledge was not significantly related to a decrease in any of the substances over time (i.e., the slope).
