As with prior re search in this area (Teesson et al., 2002; Langbucher et al., 2004; Lynskey and Agrawal, 2007; Martin et al., 2006; Gillespie et al., 2007), the present study found that DSM-IV criteria for cannabis use disorders tend to identify pathology at the moderate and more severe range of severity but do not provide indicators of the milder range. Ideally, diagnostic criteria for cannabis use disorder would show highly discriminating items with different thresholds arrayed more broadly across the severity continuum. The need for new symptom criteria to better define and measure the milder end of the cannabis use disorder continuum was addressed in this study by adding a cannabis use variable to the factor and IRT models. Analyses of abuse and dependence criteria with and without the consumption criterion produced models with good overall fit for a one-factor solution and the cannabis use criterion defined the mild end of the cannabis use disorder continuum in the IRT analysis. Further, the results of the IRT analyses showed that adding this cannabis use criterion did not substantially improve the
