Overall, for the QUANTDEP measure, the loadings for the alcohol and cannabis criteria appear generalizable to general population studies (Lynskey and Agrawal, 2007; Saha et al., 2006); in contrast, those for cocaine and opioid dependence are higher (typically > 0.9). In COGA, cocaine (7-12%) and opioid (2-5%) dependence criteria were less commonly endorsed than those for alcohol (15-51%) and cannabis (9-19%), with the former also showing less range in endorsement rates (i.e. each dependence criterion was equally likely to be endorsed). In SAGE, cocaine dependence criteria (17-19%) were somewhat more commonly endorsed than cannabis (12-18%) dependence criteria, yet the cocaine criteria had higher loadings than the cannabis criteria, identical to COGA. For both cocaine and opioids, the range of prevalence of individual criteria was highly restricted (e.g. 6-7% for opioid criteria). Thus, in both COGA and SAGE, the likelihood of endorsement of each of the 7 dependence criteria for cocaine and opioids was similar while certain alcohol and cannabis criteria (e.g. tolerance) were endorsed more often than others (e.g. use dominates life). This may be related to the ascertainment strategy
