4. Now that you have estimated the 2-PL model for these 10 items, you can rerun the program using the 3-PL model and the 1-PL Rasch model.

To rerun the 3-PL model, go back to the models section and where you see 2-PL for each item, right-click and you will be given the option to change to the 3-PL model. Rerun the analysis and see how the parameter estimates change (noting that the g parameter in the output is what we normally refer to as the c parameter in the text). If you want to run the Rasch model, make sure that the model chosen is the 2-PL model and click the button “Constraints.” From there, highlight all of the values in the a parameter column (i.e., selecting the a parameters for all 10 items).

Questions