Data are from the Collaborative Study on the Genetics of Alcoholism (COGA). Phase I data were collected at six venues between 1990 and 1999, and Phase II data between 1997 and 2004 (Edenberg et al. 2004). Only Phase II data were used in these analyses because key independent variables were not collected in Phase I. COGA relied on a complex, availability-based, family selection strategy (Reich 1996). In brief, probands with alcohol dependence were recruited at inpatient and outpatient treatment facilities through random selection procedures. After determining probands’ family distributions of alcohol dependence, densely affected nuclear and multigenerational families were identified and invited to participate. In addition, a group of control probands and their families were recruited from church congregations, large corporations, dental clinics, driver’s license bureaus, and health maintenance organizations to serve as community controls. Probands and first-, second-, and third-degree relatives who agreed to participate provided blood samples for DNA analysis, completed a structured psychiatric interview, and provided data on personality traits, family history, and psychosocial measures.
