Al-Hikmah University Journal

This study investigated the comparison of methods to detect Item Parameter Drift in National Business and Technical Examination Board (NABTEB) Senior School Certificate Examinations (SSCE) for 2012 – 2015 Chemistry multiple choice tests.  It specifically aimed to ascertain the levels of drifted items and compare the differences in the number of drifted items across the stated examinations years using four methods (Robust–z, 3-sigma IRT, Delta plot and Mantel–Haenszel methods) of detecting IPD. This study was guided by four research questions and one hypothesis. The study adopted the survey research design. The population of the study was 3,239 scores of candidates who sat for the National Business and Technical Examination Board, NABTEB, SSCE Chemistry multiple choice tests in the first administration and 8,605 Senior Secondary School SS3 Chemistry students considered for second administration, making a total population of 11,844 in Edo State, Nigeria. The sample size used for the study was 5,040 which comprised 3,239 and 1,801 candidates’ scores in first and second administrations respectively. Multistage sampling technique was employed. The instruments used to generate data were 50-item National Business and Technical Examination Board, NABTEB, SSCE Chemistry multiple choice test items each  for the four years (2012, 2013, 2014 and 2015)  making a total of 200 items. Using Cronbach Alpha, the reliability coefficients of the instruments obtained were 0.83, 0.85, 0.89 and 0.87 for the respective years. However, the item parameters were estimated from candidates’ responses using eIRT software. The four methods (Robust- z method, 3 -sigma IRT method, Delta plot method and Mantel -Haenszel methods) were used to establish the IPD, while descriptive statistics of frequency count and percentage were used to answer the research questions, and the hypothesis was tested using Chi-square statistics at 0.05 alpha level. The results that were obtained from the analysis showed that 20 items, 80 items, 65 items and 151 items drifted using Robust-z method, 3-sigma IRT method, Delta plot method and Mantel-Haenszel method respectively in 2012 to 2015 NABTEB SSCE Chemistry multiple choice tests, and it was also found that there is a significant difference in the number of drifted items in 2012 to 2015 NABTEB SSCE Chemistry multiple choice test items using Chi-square statistics. Furthermore, it was concluded that Robust-z method was the most stable method because it flagged the least number of drifted items of all the four methods. Among others, it was recommended that NABTEB and other examination bodies should use Robust -z method to detect drift items to avoid false identification of drifted items.