The item characteristic curves (ICCs) for the lifetime DSM-IV alcohol abuse and dependence symptom parameters are shown in Figure 2. ICCs graphically display the severity and discrimination parameters and facilitate a visual comparison of parameters across symptoms. The x-axis for these figures represents the latent liability to AUDs expressed as z-scores standardized in the community sample. As shown in Figure 2, item discrimination parameters ranged from 0.61 (Quit/Control) to 1.51 (Withdrawal). Item severity parameters, which are scaled to represent z-scores standardized in the community sample, were lowest for Tolerance and highest for Quit/Control. The severity parameters were generally between 2 and 3.5 standard deviations above the mean of the community sample.
