Edukacja 04_2018 okladka


The article compares two methods used to detect differential item functioning (DIF) of dichotomously scored items: a nonparametric solution based on the Mantel–Haenszel procedure (MH) and a parametric IRT approach with a likelihood ratio test. A Monte Carlo experiment was performed in order to evaluate performance of both statistics in various conditions of DIF uniformity. Results confirmed the theoretical prediction that the MH test has greater statistical power in detecting uniform DIF than the likelihood ratio test and less power than the LR test in cases of non-uniform DIF. Apart of examining statistical power of the test, specific measures of DIF effect size were compared: MH D–DIF and three measures of P–DIF expressed on the item easiness scale.

Bartosz Kondratek, Magdalena Grudniewska, Student Performance Analysis Unit, Educational Research Institute