A script for running a 2PL dichotomous item response theory analysis on the openly available LSAT data from ltm package in R
The script will let you output all parameter estimates for a 2PL or 3PL model and the following figures:
1. A scree-plot to check unidimensionality
2. Q3 statistic matrix to check for local dependence:
Example from this tutorial with no locally dependent items:
Example from another dataset with locally dependent items highlighted in blue and red:
3. Item Characteristic Curves:
Example from this tutorial:
Example from another dataset with variety of discriminability values:
4. Test/Item Characteristic Curves:
