“…In practice, most studies on substance consumption focused on a few number of substances at a time, such as cannabis (Kokkevi, Gabhainn, Spyropoulou, and the Risk Behaviour Focus Group of the HBSC, 2006), tobacco, and alcohol (Jackson, Sher, Wood, & Bucholz, 2003), or a group of substances altogether, such as 'illicit drugs' (Kandel, Treiman, Faust, & Single, 1976;Sutherland & Willner, 1998;Degenhardt, Hall, & Lynskey, 2001;Hao, Su, Xiao, Fan, Chen, Liu, & Young, 2004). Other papers considered patterns of use, but for one drug only (Harding, 1988;Epstein, Labouvie, McCrady, Swingle, & Wern, 2004;Stranges, Notaro, Freudenheim, Calogero, Muti, Farinaro, Russell, Nochajski, & Trevisan, 2006;Velicer, Redding, Anatchkova, Fava, & Prochaska, 2006;Daniulaityte, Carlson, & Siegal, 2007). Few papers dealt with the actual patterns of use, i.e.…”