Application of the multidimensional 4-parameter logistic model in the estimation of the psychometric qualities of the West African Senior School Certificate chemistry examination

In the study reported on here we assessed the dimensionalities and trends in psychometric qualities of the West African Senior School Certificate chemistry examination (WASSCCE) by applying a multidimensional 4-parameter logistic model of item response theory. Trend study was adopted as the design of the study. Four thousand students (n = 4,000) participated in the study and were selected using a multi-stage sampling procedure. The data were collected through the direct delivery technique. Research question 1 was answered using the normal ogive harmonic analysis robust method while questions 2, 3, 4, and 5 were answered using the multidimensional 4-parameter logistic model of item response theory. Microsoft Excel was employed to show trends in the psychometric qualities. The results show that only 1 factor underlies the WASSCCE for 2015 and 2016 while 2 factors underlie WASSCCE for 2017 and 2018. The results shows that WASSCCE for 2015 to 2018 were all multidimensional tests and that the items in WASSCCE 2015 were more difficult than those of 2016, 2017 and 2018. Based on the study we recommend that the psychometric qualities of tests should be determined to understand and adequately compare the quality and performance of the examinees that take the tests.