Five studies evaluated the internal consistency of the screening scales in general population samples using Cronbach's coefficient α (Table 2). Analyses suggest high consistency of at least .72 for all four instruments, with the highest value being for PUM [14] and the lowest value for CUDIT [9]. On the other hand, item-total correlations reported in two studies were only moderate varying remarkably across items. Thus, kappa indices were low to moderate for single pairs of items of the CAST [15]. In addition, corrected item-total correlations of the CUDIT were modest for most items, while inacceptable for items 2 (usual hours being stoned) and 9 (injuries) [9].
