To rule out the need for a two-parameter item response theory (IRT) model during item analysis by Rasch models, it is important to check the Rasch model's assumption that all items have the same item discrimination. Biserial and polyserial correlation coefficients measuring the association between items and restscores are often used in an informal…

Reviews the most recent version of the BILOG computer program, which estimates item and trait level parameters for the one-, two-, and three-parameter logistic unidimensional Item Response Models for dichotomously scored data. Finds this version useful. (SLD)

This study examined how well current software implementations of four polytomous item response theory models fit several multiple-choice tests. The main conclusion is that fitting polytomous item response models to multiple-choice item responses is more complex than fitting the three-parameter logistic model to dichotomously scored responses. (SLD)