Gender-related Differential Item Functioning and Differential Test Functioning in National Entrance Exams Organized by National Organization for Educational Testing

Document Type : Original Article



The performance measurement of examinees through exerting statistical control on their ability may reveal different results in different gender groups. In this case, gender-related differential item functioning and differential test functioning as well as item/test bias is likely to occur. The main purpose of this research was to investigate the gender-related DIF/DTF and gender-related bias throughout national entrance exams in Iran. Then, special tests of a test booklet in 5 experimental groups participating in national entrance exams were chosen from 2008 to 2011 through one-stage cluster sampling method. Next, logistic regression and item response theory were used to investigate DIF and DTF, respectively. The results showed that, on average, about 14% of investigated test items had gender-related DIF with negligible effect size (EF<0.0001) and about 2% of them were biased against females or males based on experts’ viewpoints. Concerning the DTF analysis, it was shown that except for Dramatic Creativity Test of Art Group, which was a bit biased against females, the other tests were not characterized with DTF.