In the Graphs window, click on "Empirical Option Curves" (no Probability). Each curve has a different color. Then click on "Legend". The color for each option is shown below the graph.
This shows the probability of choosing each option for a multiple-choice item (MCQ) as a trace line. The ascending option should be the correct response. The other options should be the incorrect distractors.
The "Empirical Option Curves" button and curves are active when Winsteps has the required information beyond that displayed in the "Empirical Category Curves". This happens when
1) "Display by item" is checked on the Winsteps Graphs menu.
and
2) The data have a scoring key or other rescoring commands.
See, for instance, Robert L. Brennan, "Educational Measurement", chapter: "Test Development'.
