Differential Item Functioning In Polytomous Items

Several recent studies have investigated the application of statistical inference procedures to the analysis of differential item functioning (DIF) in test items that are scored on an ordinal scale. Mantel's extension of the-Mantel-Haenszel test is a possible hypothesis-testing method for this purpose. The development of descriptive statistics for characterizing DIF in polytomous test items has received less attention. A statistic that appears well-suited as a summary index was proposed by Dorans and Schmitt. In this paper, two possible standard error formulas for this statistic are derived and evaluated, hypothesis testing procedures based directly on this descriptive statistic are outlined, and the results of applications to simulated data are presented. Three tables are included. (Contains 29 references.) (Author) Reproductions supplied by EDRS are the best that can be made from the original document