摘要：This paper presents an open source tool for computing extended Rasch models. It is realized in R (R Development Core Team, 2006) and available as package eRm. In addition to ordinary Rasch models extended models such as linear logistic test models, (linear) rating scale models and (linear) partial credit models can be estimated. A striking feature of this package is the implementation of conditional maximum likelihood estimation techniques which relate directly to Rasch's original concept of specific objectivity. The mathematical and epistemological benefits of this estimation method are discussed. Moreover, the capabilities of the eRm routine with respect to structural item response designs are demonstrated.
关键词：Extended Rasch models, CML estimation, specific objectivity, eRm-package.
