title: Identification of Differential Item Functioning in Multiple-Group Settings: A Multivariate Outlier Detection Approach.
abstract: We focus on the identification of differential item functioning (DIF) when more than two groups of examinees are considered. We propose to consider items as elements of a multivariate space, where DIF items are outlying elements. Following this approach, the situation of multiple groups is a quite natural case. A robust statistics technique is proposed to identify DIF items as outliers in the multivariate space. For low dimensionalities, up to 2-3 groups, a simple graphical tool is derived. We illustrate our approach with a reanalysis of data from Kim, Cohen, and Park (1995) on using calculators for a mathematics test.
authors.affiliation: a University of Liège, K. U. Leuven.
authors.forename: David
authors.initials: D
authors.lastname: Magis
authors.affiliation: b University of Amsterdam and, K. U. Leuven.
authors.forename: Paul
authors.initials: P
authors.lastname: De Boeck