Using the raschtree function for detecting differential item functioning in the Rasch model

The psychotree package contains the function raschtree, that can be used to detect differential item functioning (DIF) in the Rasch model. The DIF detection method implemented in raschtree is based on the model-based recursive partitioning framework of Zeileis, Hothorn, and Hornik (2008) and employs generalized M-fluctuation tests (Zeileis and Hornik 2007) for detecting differences in the item parameters between different groups of subjects. The statistical methodology behind raschtree is described in detail in Strobl, Kopf, and Zeileis (2010). The main advantage of this approach is that it allows to detect groups of subjects exhibiting DIF, that are not pre-specified, but are detected automatically from combinations of covariates. In this vignette, the practical usage of raschtree is illustrated.