IRT Illustrator

IRT Illustrator is a pure Java application that allows you to quickly plot various item response theory (IRT) functions. The interface is interactive, which allows you to make changes on the fly and see the result instantly.

The application currently support the Rasch, 2PL, 3PL, and 4PL binary item response models and the partial credit (PCM), generalized partial credit (GPCM), and graded response (GRM) models. In addition to the item or option characteristic curves, you can also plot the item and test information functions, item and test standard error functions, and the test characteristic curve. A single chart may contain curves for a single item or multiple items. In addition, you can overlay multiple functions on a single chart such as item characteristic curves and the test information.Once you have created a chart, save it as either a PNG or JPG file.

The interactive feature allows you to watch how the chart changes as you add items or other functions to the chart. For example, you can watch how the test information function changes as you add items to the chart.

Sample Charts