ABSTRACT
This chapter consists of three parts. The first part describes the development of DSM rational function models (RFMs) based on mapping Rasch model parameters on the D-scale. The second part presents the mathematical equivalence between the latent two-parameter RFM model and the two-parameter logistic model in item response theory. The third part describes a practically efficient approach to presenting D-scores, obtained via different estimation methods, on a common D-scale.
