Abstract

The study examined the differential item functioning (DIF) of 2018 Basic Education Certificate examination (BECE) in Mathematics tests of National Examination Council (NECO) and BECE of Akwa Ibom State government in Nigeria. The invariance in the tests with regards to sex was considered using Item Response Theory (IRT) approach. The study area was Akwa Ibom state of Nigeria having a student population of 58,281 for the examination. The sample was made of up 3810 students drawn through a multi-stage sampling approach. The multidimensional IRT (MIRT) package implemented in R-programming language software was applied in analyzing the data. The findings reveal that BECE of NECO displayed 23(38.3%) DIF items while BECE of Akwa Ibom State had 37 (61.7%) DIF items in terms of sex. The findings also revealed that, in the two examinations, more items favoured the male candidates more than the female candidates in terms of performance. It was recommended that IRT model should be adopted by test developers to determine item parameters for selection of good items to ensure quality of items before administration. Test equating of students who write equivalent form examinations conducted by different examining bodies was also recommended for admission and placement of candidates to determine actual group differences in performance. The study posits that research on Differential Item Functioning is inconclusive, so should be encouraged.