Analysis of Differential Item Functions of Mathematical-Economics Item Structured Test Forms Based on Item Difficulty Levels in Colleges of Education, Enugu State, Nigeria

The study of Mathematical-economics is paramount to all the Economics students in Nigerian tertiary institutions in the enhancement of growth and nation development. In actualizing the dream goal of the subject two modern theories were anchored thus: Classical Test Theory (CTT) and Item Response Theory (IRT) to evaluate the study. Hence, the researchers evaluated differential item functions of Mathematical-economics item structured test forms (easy-to-hard, hard-to-easy and randomversions) based on item difficulty levels in colleges of education, Enugu State, Nigeria. Three research questions guided the study and co-relational research design was adopted. The population of study consisted of all 6420 Federal, State, and Private NCE 1 Economics students 2018-2019 academic season and a simple random sample of 610 NCE1 Economics students were selected for the study. Mathematical-Economics Achievement Test (MEAT) was used for data collection. MEAT was validated which yielded 0.86 validity index and 0.84 reliability index. Data were analyzed using factor analysis (TID,MH, LR CTT-based andX2 and Raju’s IRT-based). The result reveals that examinees gain advantages of easy-to-hard than hard-easy or even a random version test forms and differential item structured correct responses to the items for examinees with the same ability levels. It was recommended that economics lecturers in colleges of education should use easy-to-hard test form to evaluate examinees considering with psychometric functions of evaluation for valid decisions.