Detection of differential item functioning with the difR package

The purpose of this talk is to briefly present the package difR of the software R. This package permits to identify differential item functioning (DIF) with several parametric or nonparametric methods. Nonparametric methods include: Mantel-Haenszel, standardization, logistic regression and Breslow-Day. Available parametric methods are the Lord’s chi-square test, the Raju’s area method, and the likelihood-ratio test. Some methods for DIF identification in multiple groups (generalized Mantel-Haenszel, generalized Lord’s test) are also available. The presentation focuses on the package and its potential, rather than on the included methods. Its performance will be illustrated with an example data set.