Test fairness and assessment of differential item functioning of mathematics achievement test for senior secondary students in Cross River state, Nigeria using item response theory

Abstract

This study used Item Response Theory approach to assess Differential Item Functioning (DIF) and detect item bias in Mathematics Achievement Test (MAT). The MAT was administered to 1,751 SS2 students in public secondary schools in Cross River State. Instrumentation research design was used to develop and validate a 50-item instrument. Data were analysed using the maximum likelihood estimation technique of BILOG-MG V3 software. The result of the study revealed that 6% of the total items exhibited differential item functioning between the male and female students. Based on the analysis, the study observed that there was sex bias on some of the test items in the MAT. DIF analysis attempt at eliminating irrelevant factors and sources of bias from any kind for a test to yield valid results is among the best methods of recent. As such, test developers and policymakers are recommended to take into serious consideration and exercise care in fair test practice by dedicating effort to more unbiased test development and decision making. Examination bodies should adopt the Item Response Theory in educational testing and test developers should therefore be mindful of the test items that can cause bias in response pattern between male and female students or any sub-group of consideration. Keywords: Assessment, Differential Item Functioning, Validity, Reliability, Test Fairness, Item Bias, Item Response Theory.