Abstract
Detection of differential item functioning in a science test. Using National Asessment of Educational Progress (NAEP) resources, a study was carried out to determine the presence of differential functioninig of the items of a Science Test between 13-yearsold Spanish boys and girls as a first step in the identification of biased items. A variation of the standard Mantel-Haenszel procedure proposed by Mazor, Clauser and Hambleton (1994) and a residual analysis procedure based on IRT techniques, proposed by Prieto, Barbero and San Luis (1996), are used in an iterative way to detect items showing differential functioning. Results from this work suggest that statistical procedures for detecting DIF may be improved by applying them in an iterative way, and that the application of several strategies to the same pool of data may lead to obtain more reliable conclusions about the identification of possible biased items.
