Select by clicking on "Multiple Item ICCs" or from the Graphs menu. This enables the display of multiple model and empirical ICCs on the same graph. Click on the "Model" and "Empirical" curves you wish to display. Click again on your selection to clear it.
The x-axis can use absolute scaling relative to the latent trait (as in this Figure) or scaling relative to each item difficulty.
Displayed are the selected model and empirical ICCs. A similar technique is used to display DIF item characteristic curves for non-uniform DIF.