As described previously, the emotional symptoms scale of the SDQ consists of 5 items, relating to different manifestations of internalizing. For each item, we created a binary variable that was coded 0 if an individual’s mother had always reported that her child had never exhibited that symptom/behavior, or 1 if the child had ever exhibited that symptom/behavior (e.g., “somewhat true” or “certainly true” in at least one assessment). We then examined whether these binary variables were associated with alcohol use at age 13.8, in the context of a single-stage model including all 5 item-level binary variables, along with sex, maternal depression, and income as covariates.
