Differential Item Functioning Using Robust Scaling R package robustDIF version 0.2.0 Provides tools for testing differential item functioning (DIF) and differential test functioning (DTF) in two-group item response theory models. The package estimates robust scaling parameters via iteratively reweighted least squares with Tukey's bisquare loss, and supports Wald-type tests of item-level and test-level differences from robust scaling parameters. Inputs can be supplied directly from model parameter/covariance objects or extracted from fitted 'mirt' and 'lavaan' models. Methods are described in Halpin (2022) <doi:10.48550/arXiv.2207.04598>. Software Depends: R(>= 3.5.0), Matrix Imports: mirt, lavaan Suggests: testthat (>= 3.0.0) Peter Halpin <peter.halpin@unc.edu> Comprehensive R Archive Network (CRAN) Peter Halpin [aut, cre], Kyle Nickodem [ctb], James Eagle [ctb] GPL (>= 3) 2026-04-21 application/tgz https://CRAN.R-project.org/package=robustDIF doi:10.32614/CRAN.package.robustDIF