Equating General Education Diploma Results of Physics Examination in the Sultanate of Oman Using Item Response Theory

The study aimed to equate General Education Diploma results of physics exam in the Sultanate of Oman using Item Response Theory (IRT) and setting them in a common scale. The study sample included all of the General Education Diploma students both male and female who passed the physics exam in the academic years 2014/2015 and 2015/2016 with atotal sample of (17175 & 18966) respectively. Two different copies of physics exam were used for the purpose of the study. The first one consisted of 40 items and the other was 36 items. The data was analyzed by Multilog 7.03 program, to estimate the parameters of the items and the abilities of examinees and to check the IRT hypotheses. Moreover, the method of True Score Equation was used. The Results showed that there are no statistically significant differences between the means of the true scores of the criteria exam and the results, which were equated to the new exam. The equation accuracy was checked by Equating Bias method