Abstract
<p>In various research settings, responses to questionnaire items are continuously distributed and bounded from below and above. Suitable item response theory (IRT) models are available for the response data; however, implementations of these models differ significantly in their estimation method, availability, and user-friendliness. These differences hamper the application of such models in general, and model fit comparison in particular. Therefore, in this paper, BoundIRT is presented, which implements four popular bounded IRT models from the literature in the R statistical computing environment. The package provides various facilities for model estimation and model fit assessment. In addition, once a suitable model has been established for a given dataset, the factor score regression facilities can be used to conduct regression analyses of the latent variable in the model with respect to other variables.</p>