DIFSIB: A SIBTEST Package.

The R package DIFSIB provides a direct translated version of the SIBTEST, Crossing- SIBTEST, and POLYSIBTEST procedures that were last updated and released in 2005. Having these functions directly written from Fortran into R code will allow researchers and practitioners to easily access the most recent versions of these procedures when they are conducting differential item functioning analysis and continue to improve the software more easily.