At both the T20 and the ongoing T25 followups of these families, offspring age 12 or older were evaluated using questions from the adolescent version of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) instrument developed by the Collaborative Study on the Genetics of Alcoholism (COGA) (Bucholz et al., 1994; Hesselbrock et al., 1999). These included questions on alcohol, drug, and mental health histories. Overall, the SSAGA has a 1-week reliability of .86 for alcohol-related items and similar validities compared with a second standard interview (Bucholz et al., 1994; Hesselbrock et al., 1999; Kuperman et al., 2001a). Note that in order to use data gathered at the age closest to the onset of drinking, the offspring data used in these analyses were from their first interview after drinking occurred (T20 or T25).
