[Application of four procedures for detecting differential item functioning in polytomous items]

The authors describe and use four methods for detecting Differential Item Functioning in polytomous items: Mantel, Generalized Mantel-Haenszel (GMH), Ordinal Logistic Regression (RLO), and Discriminant Logistic Regression (RLD). For each procedure, the theoretical model and the measure of effect size are described. The data from the "Reading Comprehension Test" from the PISA2000 evaluation program were analyzed using a cross-validation design. Two booklets were independently evaluated in the American and Spanish samples. Adopting as decision rule the significance of the statistical test and the measurement of the effect size, agreement among the evaluated procedures was total for two of the analyzed items.