Person Fit R package PerFit version 1.4.7 Several person-fit statistics (PFSs; Meijer and Sijtsma, 2001, <doi:10.1177/01466210122031957>) are offered. These statistics allow assessing whether individual response patterns to tests or questionnaires are (im)plausible given the other respondents in the sample or given a specified item response theory model. Some PFSs apply to dichotomous data, such as the likelihood-based PFSs (lz, lz*) and the group-based PFSs (personal biserial correlation, caution index, (normed) number of Guttman errors, agreement/disagreement/dependability statistics, U3, ZU3, NCI, Ht). PFSs suitable to polytomous data include extensions of lz, U3, and (normed) number of Guttman errors. Software Depends: ltm, mirt Imports: stats, graphics, fda, Hmisc, irtoys, MASS, Matrix Jorge N. Tendeiro <tendeiro@hiroshima-u.ac.jp> Comprehensive R Archive Network (CRAN) Jorge N. Tendeiro [aut, cre] GPL (>= 2) 2025-04-02 application/tgz https://CRAN.R-project.org/package=PerFit doi:10.32614/CRAN.package.PerFit