Consistent with the well-established understanding that clinical samples consist of more severe cases than those in the general population (Cohen and Cohen, 1984), severity of individual substance use disorder criteria (in IRT, indicated by infrequent occurrence) in this study was far lower than that found in non-clinical samples. Many severity estimates in this sample were around zero and even negative, indicating that even individuals below average in the sample on the latent (disorder) trait would have at least a 50% probability of experiencing the criterion.
