The IRT Procedure

uses the Rasch model; one-, two-, three-, and four-parameter models; graded response model with logistic or probit link; and generalized partial credit model

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 (ML), maximum a posteriori (MAP), and expected a posteriori (EAP) methods