Comparison of Item Parameter Estimates of Traditional True Score Theory and Modern Mental Theory in Oyo State Junior Secondary School Certificate Mathematics Examination

The study compared the Traditional True Score Theory (TTST), and Modern Mental Test Theory (MMTT) estimated item parameter indices to the ability of examinees in Junior Secondary School Certificate Examination (JSSCE) in Mathematics. This is with the view of providing empirical justification on the appropriateness of decisions made statistically from psychometric tests. The study adopted a descriptive survey design. A sample of 600 students was randomly selected from a population of 95,419 students who sat for the 2016 JSSCE Mathematics Paper 1 in Oyo State, Nigeria. An adoption version of the 2016 Oyo State JSSCE Mathematics Paper 1 titled Mathematics Test (MT) instrument was utilized for information aggregation. Data collected were analyzed using SPSS and BILOG-MG software packages. The effects indicated that the difficulty indices of Mathematics test items based on TTST ranged from 0.00 to 0.65. The discrimination indices ranged from 0.00 to 0.41. Fifty-two items (86.67%) on the MT items had moderate item difficulty (0.200 ≤ p ≤ 0.620). On the other hand, 42 (70%) on the items discriminate poorly (0.10 ≤ D ≤ 0.29). Regarding MMTT results, item difficulty parameter ranged between 0.216 and 7.988 for 2PLM while the discrimination parameter ranged between 0.100 – 0.729 respectively. Furthermore, there was a negative relationship between the difficulty indices of MMTT and TTST models (r = -0.702, p < .01). The concomitance correlation for discrimination was positive (0.646, p <. 01). The study concluded that the Oyo State 2016 JSSC Mathematics examination was of a moderate psychometric quality irrespective of the theoretical measurement model used in the appraisal.