Discrimination parameters across all substances ranged from 1.09 to 6.18 (Table 3; Fig. 2) indicating that each criterion had a strong ability to delineate individuals who were higher vs. lower on the latent trait. For example, the discrimination estimate of 3.13 for the abuse criterion of social/interpersonal problems indicates that an increase of one standard deviation on the latent trait results in a exp(3.13) = 22.9-fold increase in the odds of having the social/interpersonal abuse criterion. The severity parameters (Table 3; Fig. 2) calibrated to the observed sample, estimate the point above or below the mean of the latent trait (in standard deviations) at which 50% of the population will endorse that criterion. In this clinical sample, the severity estimates of ≤0.0 indicate that even patients below average on the latent trait have at least a 50% probability of experiencing the criterion.
