SAS/STAT Software

IRT Procedure

The IRT procedure fits item response theory models. The following are highlights of the IRT procedure's features:

  • fits the following types of models:
    • Rasch model
    • one-, two-, three-, and four-parameter models
    • graded response model with logistic or probit link
    • generalized partial credit models for ordinal items
  • enables different items to have different response models
  • performs multidimensional exploratory and confirmatory analysis
  • performs multiple-group analysis, with fixed values and equality constraints within and between groups
  • estimates factor scores by using maximum likelihood, maximum a posteriori, and expected a posteriori methods
  • displays the polychoric correlation matrix and a heat map for the polychoric correlation matrix
  • displays item characteristic curves and test information curve plots
  • create a SAS data set that corresponds to any output table
  • automatically creates graphs by using ODS Graphics

For further details see the SAS/STAT User's Guide: The IRT Procedure