Abstract

The study ascertained unidimensionality approach to differential item functioning in Economics multiple choice standardized test in Nigeria. Three research questions were asked and three hypotheses were formulated to guide the study. The design of this study was a survey which involvedthe inferential method. The population of the study was 4,434,979 secondary school students in the 11,875 public secondary schools in the 36 states including Abuja the Federal Capital Territory (FCT) of Nigeria. The sample comprised of seven hundred and ninety eight (798) students involving purposive and simple random sampling techniques. The instruments for data collection were SocioDemographic Inventory (SDI) and a 50 item WAEC General Economics Paper I Multiple Choice Test. The instruments were revalidated by five specialists: three in Educational Measurement and Evaluation and two from Economics Education from Michael Okpara University of Agriculture Umudike and Imo State University, Owerri. The reliability ofthe test was established using KuderRichardson formular 20 (KR-20) statistics with an index of 0.80. In answering the research questions, binary logistic regression statistics was used while the hypotheses were tested using Wald test associated with binary logistic regression statistics at 0.05 level ofsignificance. Result of the analysis revealed among others that; 13, 9 and 18 items in 2015 WAEC violated the unidimensionality principle or assumption of IRT with respect to gender, location and socio-economic status respectively. Based on the findings, it was recommended that; examining bodies, psychometricians, government, private firms, and all other stakeholders should explore the use of differential item functioning in the detection of bias test items in any examination.