Nonlinear CUB models: the R code

Nonlinear CUB models have been recently introduced in the literature to model ordinal data taking into account the unequal spacing among response categories. Nonlinear CUB models can be effectively used in a variety of fields, typically when human perceptions and attitudes are measured by questionnaires with questions having ordered response categories. This paper introduces the code developed in the free software environment R for Nonlinear CUB estimation, graphical representation of a variety of outputs, fit evaluation, along with data simulation according to the Nonlinear CUB data generating process.