For analyzing item response data, item response theory (IRT) models treat the discrete responses to the items as driven by underlying continuous latent traits, and consider the form of conditional probability of the response to each item given the latent traits. In a similar fashion, log-linear...

Given the rapid advancement of computer technology, the importance of administeringadaptive tests with polytomous items is in great need. With regard to the applicability ofadaptive testing using polytomous IRT models, adaptive testing can use polytomous items of either rating scales, or in some...

The Rasch family of models considered in this paper includes models for polytomous items and multiple correlated latent traits, as well as for dichotomous items and a single latent variable. An R package is described that computes estimates of parameters and robust standard errors of a class of...