However, subsequent analyses reveal that a substantial number of individuals are inaccurately categorized on the basis of AUD severity. The top two panels of Figure 4 display the distribution of individuals’ AUD severity separated by diagnostic category for persons endorsing 1 or more abuse or dependence symptoms. The IRT-based severity estimates (top right panel) are scaled to have a mean of 0 and a standard deviation (SD) of 1 in the community sample and can be interpreted as standardized scores based on the community sample. The top panel of Figure 4 demonstrates that the current DSM-IV-based diagnostic system, though effective at distinguishing AUDs on average, results in substantial overlap and inconsistencies in severity across diagnostic categories. This problem is most clearly demonstrated in the top right panel of Figure 4 where IRT-based estimates of AUD severity for many of the diagnostic orphans are substantially higher (in some cases almost an entire SD higher) than severity estimates for many persons diagnosed with abuse. A similar pattern is evident across abuse and dependence. For example, some persons diagnosed with abuse have alcohol
