Currently, there is only one free IRT tool that I could finalize until today. It is Item Response Function (IRF) and Item Information Function (IIF) Graph Generator. With this easy to use tool, you are able observe the changes in IRF and IIF when the item parameters change. It is available in both xls and xlsx formats, so you need to have MS Excel to view it. Below are some screenshots from the program.
Item Response Function (IRF) and Item Information Function (IIF) Graph Generator v1.0
You simply enter the item parameters for the two preset items
The program calculates the probability of the correct responses in 7 different theta values and draws the IRF for both items
It also calculates IIF and the SE values attributed to these IIF
Click here to download
Acknowledgement : I would like to thank Prof. David J. Weiss for his suggestions to make this excel spreadsheet better.
Alper Sahin, ph.D.