For criteria showing DCF, effect sizes for were calculated for difficulty parameters showing DCF as the absolute difference in thresholds between groups and item characteristic curves (ICCs) were computed to provide a visual representation of group differences in both discrimination and difficulty (Steinberg and Thissen, 2006). In ICCs, criteria with greater discrimination will have steeper curves (i.e., higher factor loading). Likewise, criteria with greater difficulty will have higher thresholds (i.e., will correspond to higher numbers on the x-axis, representing greater severity) and will appear farther from the y-axis. Conversely, more commonly endorsed criteria tend to have lower difficulty and will appear closer to the y-axis in ICCs. A partial item information curve was also computed from the final model parameters to illustrate the aggregate information about AUD severity gleaned from the criteria showing DCF for each of the 4 groups. In the information curves, the height of the peak corresponds to measurement precision, with higher peaks having greater precision, and the kurtosis corresponds to the range of severity over which liability is measured.
