Unidimensional Item Response Theory Modeling R package irtQ version 1.2.0 Fit unidimensional item response theory (IRT) models to test data, which includes both dichotomous and polytomous items, calibrate pretest item parameters, estimate examinees' abilities, and examine the IRT model-data fit on item-level in different ways as well as provide useful functions related to IRT analyses such as IRT model-data fit evaluation and differential item functioning analysis. The bring.flexmirt() and write.flexmirt() functions were written by modifying the read.flexmirt() function (Pritikin & Falk (2022) <doi:10.1177/0146621620929431>). The bring.bilog() and bring.parscale() functions were written by modifying the read.bilog() and read.parscale() functions, respectively (Weeks (2010) <doi:10.18637/jss.v035.i12>). The bisection() function was written by modifying the bisection() function (Howard (2017, ISBN:9780367657918)). The code of the inverse test characteristic curve scoring in the est_score() function was written by modifying the irt.eq.tse() function (Gonzalez (2014) <doi:10.18637/jss.v059.i07>). In est_score() function, the code of weighted likelihood estimation method was written by referring to the Pi(), Ji(), and Ii() functions of the catR package (Magis & Barrada (2017) <doi:10.18637/jss.v076.c01>). Software Depends: R (>= 4.5) Imports: stats, statmod, utils, tibble, dplyr, purrr, tidyr, rlang, reshape2, janitor, ggplot2, gridExtra, parallel, Matrix, Rfast, mirt Suggests: knitr, rmarkdown, testthat (>= 3.0.0), pkgdown, RhpcBLASctl Hwanggyu Lim <hglim83@gmail.com> Comprehensive R Archive Network (CRAN) Hwanggyu Lim [aut, cre], Craig S. Wells [ctb], James Howard [ctb], Joshua Pritikin [ctb], Jonathan P Weeks [ctb], Jorge Gonzalez [ctb], David Magis [ctb] GPL (>= 2) 2026-07-27 application/tgz https://CRAN.R-project.org/package=irtQ doi:10.32614/CRAN.package.irtQ