IRT, A PANACEA IN DETECTING DIFFERENTIAL FUNCTIONING (DF) IN JUNIOR SECONDARY SCHOOL MULTIPLE-CHOICE MATHEMATICS TEST IN 2019 AND 2020 EFFECTIVE STUDENTS' PERFORMANCE

The study aimed at determining IRT, a panacea in detecting differential functioning (DF) in junior secondary school multiple-choice mathematics test in 2019 and 2020 effective students’ performance in Delta State. Two research questions guided the study. The multiple triangulation research design was adopted. The population comprised of 140,939 public school upper Basic three students in Delta state, Nigeria. The study involved a sample of 1000 students. The students were selected from schools across the various local government that made up Delta state using proportionate stratified sampling and sample random sampling techniques. The primary instrument for this study was the Mathematics Achievement Test (MAT), which was adopted from Examination and Standard office in Asaba The face and content validity were used to determine the validity of the instrument. The Kuder Richardson-21 was used to compute the reliability index of 0.87, The findings of the study revealed that the incidence of d-parameter issues in the 2020 BECE Mathematics multiple-choice test items in Delta State was low, Amongst others, the study recommended that examination bodies should maintain the current test development and review processes while introducing periodic refresher workshops for item writers to sustain and further improve item discrimination quality. The study contributed the following to knowledge among others: it has provided a longitudinal perspective of D-parameter item performance over two consecutive years.