G-factor models such as the bifactor model and the hierarchical G-factor model are
increasingly applied in psychology. Many applications of these models have produced …

About 45 R packages to analyze data using item response theory (IRT) have been
developed over the last decade. This article introduces these 45 R packages with their …

Currently there are many introductory textbooks on educational measurement and
psychometrics as well as R. However, there is no single book that covers important topics in …

The recently proposed class of item response tree models provides a flexible framework for
modeling multiple response processes. This feature is particularly attractive for …

A new item response theory (IRT) model with a tree structure has been introduced for
modeling item response processes with a tree structure. In this paper, we present a …

The use of bifactor models has increased substantially in the past decade. However, bifactor
models are prone to a nonidentification problem in the context of prediction that is not well …

Several decades of psychometric research have led to the development of sophisticated
models for multidimensional test data, and in recent years, multidimensional item response …

When dealing with missing responses, two types of omissions can be discerned: items can
be skipped or not reached by the test taker. When the occurrence of these omissions is …

Test items for which the item score reflects a sequential or IRTree modeling outcome are
considered. For such items, we argue that item-specific factors, although not empirically …

We present a novel application of a generalized item response tree model to investigate test
takers' answer change behavior. The model allows us to simultaneously model the observed …