Comparison of differential item functioning determination techniques: HGLM, LR and IRT-LR

The aim of this research is to determine differential item functioning (DIF) by hierarchical linear modeling (HGLM) on test items and comparing these results by the DIF results determined by logistic regression (LR) and IRT-likelihood ratio (IRT-LR) techniques. Investigating the concordance between the techniques in determining the items with DIF, we have found significant relations between items with DIF determined in Turkish and Science sub-tests using LR and IRT-LR. In Social Studies test, we have found significant relation between the results of the HGLM and LR, HGLM and IRTLR, LR and IRT-LR techniques. The number of items with DIF per gender determined by all three different techniques has been found to be almost half of the number of test items. Th ough all the level of the items determined by LR technique have been negligible, with IRT-LR technique only a very few of the items have been found with negligible DIF. Comparing the Social Studies and Science sub-tests with Turkish sub-test using HGLM technique, more than half of the items have been found to have DIF. Turkish sub-test has the maximum number of item with DIF.