Examine the IRT model-data fit on item-level in different ways as well as provide useful functions related to unidimensional item response theory (IRT). In terms of assessing the IRT model-data fit, one of distinguished features of this package is that it gives not only well-known item fit statistics (e.g., chi-square, infit and oufit statistics (Ames & Penfield (2015) <doi:10.1111/emip.12067>)) but also graphical displays to look at residuals between between the observed data and model-based predictions (Hambleton, Swaminathan, & Rogers (1991, ISBN:9780803936478)). More evaluation methods will be included in the future updated version. In addition to the evaluation of IRT model-data fit, there are several useful functions such as estimating proficiency parameters, calibrating item parameters given the fixed effects (aka. ability values) (Baker & Kim (2004, ISBN:9780824758257)), computing asymptotic variance-covariance matrices of item parameter estimates (Li & Lissitz (2004) <doi:10.1111/j.1745-3984.2004.tb01109.x>), importing item and/or ability parameters from popular IRT software, generating simulated data, computing the conditional distribution of observed scores using the Lord-Wingersky recursion formula (Lord & Wingersky (1984) <doi:10.1207/s15324818ame1002_1>), computing item and test information functions, computing item and test characteristic curve functions, and plotting item and test characteristic curves and item and test information functions.

Version: | 1.0.0 |

Depends: | R (≥ 3.4) |

Imports: | stats, statmod, utils, reshape2, dplyr, tidyr, purrr, ggplot2, rlang, gridExtra, parallel, pbapply |

Suggests: | mirt |

Published: | 2019-08-24 |

Author: | Hwanggyu Lim [aut, cre], Craig S. Wells [ctb] |

Maintainer: | Hwanggyu Lim <hglim83 at gmail.com> |

License: | GPL-2 | GPL-3 [expanded from: GPL (≥ 2)] |

NeedsCompilation: | no |

Materials: | README NEWS |

CRAN checks: | irtplay results |

Reference manual: | irtplay.pdf |

Package source: | irtplay_1.0.0.tar.gz |

Windows binaries: | r-devel: irtplay_1.0.0.zip, r-release: irtplay_1.0.0.zip, r-oldrel: irtplay_1.0.0.zip |

OS X binaries: | r-release: irtplay_1.0.0.tgz, r-oldrel: irtplay_1.0.0.tgz |

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