Abstract
The study analysed the school type differences in differential item functioning of WASSCE Biology multiple-choice examinations of 2021 in North West Nigeria. The study adopted descriptive survey research design. One objective, research question and corresponding hypothesis was raised and tested in the study. The population of the study consisted of 412, 323 Biology students and the sample size of 1,532 Biology senior secondary school students' (SSSIII) were drawn using multistage sampling procedure. The instrument adopted and used for the collection of data was WASSCE Biology paper III used in 2021 examinations. The reliability index of the instrument
was 0.73. Binary Logistic Regression was employed in testing the hypothesis in the study at 0.05 level of significance. The results of the study indicated that WASSCE Biology multiple-choice test items used in 2021, contain test items that significantly functioned differentially for students based on school type in favour of mixed school students which placed the boys' and girls' only school at disadvantaged group in the WASSCE 2021 Biology multiple-choice test items. Based on this finding, it was recommended by the researchers that there should be more commitment by the examination bodies in using the IRT approach than the item analysis alone to ensure quality items.