Fig. 1: Discrimination distribution of item groups by cognitive levels.

The histograms display the cognitive diagnostic discrimination values for test items across four cognitive levels: memorizing (top left), understanding (top right), simple application (bottom left), and comprehensive application (bottom right). Each panel shows the frequency distribution of discrimination indices, with the x-axis representing CDM discrimination values and the y-axis representing the frequency of items. Mean, standard deviation (SD), minimum, and maximum values are provided in the top-left corner of each panel.