“…Sample sizes ranged from 34 (Romo, Lefkowitz, Sigman, & Au, 2002) to 7965 (Longmore et al, 2004), resulting in a total of over 30,000 participants. Fourteen studies had sample sizes above 500 even after a high attrition rate across studies (median attrition rate = 37%), and 5 studies had sample sizes under 200 (French & Dishion, 2003;Halpern, Udry, & Suchindran, 1998;McBride et al, 2003;Romo et al, 2002;Waller & Dubois, 2004) Nine studies were from three independent U.S. national samples (Longmore, Manning, & Giordano, 2001;Longmore et al, 2004;McNeely et al, 2002;Meier, 2003;Mott, Fondell, Hu, Kowaleski-Jones, & Menaghan, 1996;Raffaelli & Crockett, 2003;Schvaneveldt et al, 2001;Sieving et al, 2000). Other studies represented a range of areas of the U.S., with half (n = 13) of the 26 studies with non-national samples including a high proportion of ethnic minority adolescents and the other 13 including mostly white adolescents.…”