[1] Brown Univ, Ctr Alcohol & Addict Studies, Providence, RI 02912 USA
[2] Smith Coll, Stat & Data Sci Program, Northampton, MA 01063 USA
[3] Univ Massachusetts, Sch Med, Dept Quantitat Sci, Amherst, MA 01003 USA
[4] Brown Univ, Ctr Alcohol & Addict Studies, Providence, RI 02912 USA
[5] Univ Southern Calif, Suzanne Dworak Peck Sch Social Work, 669 West 34th St,MRF 214, Los Angeles, CA 90089 USA