In S4S, we used both clinical and non-clinical phenotypes meant to match the phenotypes used in COGA. Indicators included: (1) alcohol dependence, (2) alcohol abuse, (3) high school antisocial behavior, (4) college antisocial behavior, and (5) a count of illicit drug use. The first principal component accounted for approximately 68% of the common variance among the externalizing variables in COGA and 42% in S4S. A full description of the externalizing score construction can be found in the supplemental material (Section 2).
