Select by clicking on "Cumulative Probabilities" or from the Graphs menu.

 

Lines: This shows the modeled category probability curves accumulated so that the left-hand curve (red) is the probability of being observed in the lowest category. The next curve (blue) is the probability of being observed in the lowest or next lowest category. And so on to the right.

 

Arrows: The points of intersection between these curves and the 0.5 probability line are the Rasch-Thurstone thresholds. The points at which being observed in this category (or below) and the category above (or higher) are equal. These curves are always in the order of the category scores.

 

Buttons are described in Graph window.

 

Click on the "Flip Curves Vertically" button to change the vertical direction of the curves.