Differential Item Functioning (DIF) in Mathematics Test Using Mantel - Hsaenzel and Item - Response Theory

Tests should be fair for all individuals of any gender, race, age, and socioeconomic status. Accordingly, the assessment of item bias and differential item function (DIF) are very important. In this study, the gender differential item function has been studied using Mantel - Haenszel and item response theory (IRT). First, the theoretical framework and evaluation methods of DIF are introduced. Then in order to offer a practical application of the method, responses of a stratified random sample of 4000 subjects Consisting of 2200 males and 1800 females to 55 items of Mathematics test of National University Entrance Exam has been analyzed. The results Reveals the presence of gender DIF on the test items. In assessing DIF using Mantel – Haenszel Methods, 23 items had significant Mantel - Haesnzel index. Based on IRT 9 items had gender DIF, which all of them were in favor of females. The content investigation of the items with gender DIF indicated that most items with DIF in favor of females are in content domain of functions and equations while items with DIF in favor of males are in field of trigonometry, geometry and probability.