Person misfit and person reliability indices in item response theory (IRT) can play an important role in evaluating the validity of a test or survey instrument at the respondent level. Prior empirical comparisons of these indices have been applied to binary item response data and suggest that the two types of indices return very similar results.…

This paper presents a mixture item response tree (IRTree) model for extreme response style. Unlike traditional applications of single IRTree models, a mixture approach provides a way of representing the mixture of respondents following different underlying response processes (between individuals), as well as the uncertainty present at the…

Four-parameter models have received increasing psychometric attention in recent years, as a reduced upper asymptote for item characteristic curves can be appealing for measurement applications such as adaptive testing and person-fit assessment. However, applications can be challenging due to the large number of parameters in the model. In this…