Gender differential item functioning on a national field-specific test: The case of PhD entrance exam ofTEFL in Iran

Differential Item Functioning (DIF) exists when examinees of equal ability from different groups havedifferent probabilities of successful performance in a certain item. This study examined genderdifferential item functioning across the PhD Entrance Exam of TEFL (PEET) in Iran, using both logisticregression (LR) and one-parameter item response theory (1-p IRT) models. The PEET is a national testconsisting of a centralized written examination designed to provide information on the eligibility of PhDapplicants of TEFL to enter PhD programs. The 2013 administration of this test provided score data fora sample of 999 Iranian PhD applicants consisting of 397 males and 602 females. First, the data weresubjected to DIF analysis through logistic regression (LR) model. Then, to triangulate the findings, a 1-pIRT procedure was applied. The results indicated (1) more items flagged for DIF by LR than by 1-p IRT(2) DIF cancellation (the number of DIF items were equal for both males and females), as revealedthrough LR, (3) equal number of uniform and non-uniform DIF, as tracked via LR, and (4) femalesuperiority in the test performance, as revealed via IRT analysis. Overall, the findings of the studyindicated that PEET suffers from DIF. As such, test developers and policymakers (like NOET & MSRT) arerecommended to take these findings into serious consideration and exercise care in fair test practice bydedicating effort to more unbiased test development and decision making.

کلیدواژه ها:

differential item functioning ، logistic regression ، one-parameter item response theory