“…Evidence suggests that individual- and group-level background variables are important for AOD use, including ethnicity (Chen & Jacobson, 2012; Khan, Cleland, Scheidell, & Berger, 2014; Miller, Byrnes, Branner, Voas, & Johnson, 2013; Shih, Miles, Tucker, Zhou, & D’Amico, 2010), gender (Khan et al, 2014), age (Chen & Jacobson, 2012; Miller, Byrnes, Branner, Johnson, & Voas, 2013), group size (Lau-Barraco, Braitman, Leonard, & Padilla, 2012), and past AOD behavior (Miller, Byrnes, Branner, Voas, & Johnson, 2013). Several of these variables have also been related to willingness to implement protective strategies with group members at nightclubs (Byrnes, Miller, Bourdeau, Johnson, & Voas, 2016). Therefore, individual control variables included gender, ethnicity, age, and past 30-day drinking/drug use at clubs.…”