rasch - Models and Diagnostics for Rasch Measurement Theory

Fits models for Rasch Measurement Theory, whose defining measurement properties include sufficiency and invariance. Available models include the dichotomous Rasch, partial credit, rating scale, many-facet, extended frame of reference and explanatory models. Explanatory modelling supports predictors at the item and threshold levels. Comparative judgement models are available for dichotomous and ordered pairwise responses and for rankings, with support for extended frames of reference and explanatory predictors, and items or persons can be calibrated jointly from responses and judgements. Functions support estimation and examination of model fit, targeting, reliability, dimensionality, local dependence, differential item, bundle and test functioning, equating and simulation. A graphical interface for fitting models and examining results is provided through an interactive 'shiny' application.