In 2015, Faculty of Medicine Srinakharinwirot University launched the policy to divide groups of students from HRH Princess Mahachakri Sirindhorn Medical Center (MSMC) to learn Otolaryngology at Panyananthaphikkhu Chonprathan Medical Center (PCMC). To make quality control about student assessment process to ensure validity, reliability and fairness of student assessment according to Asean University Network version 3 criteria and internal curriculumassessment criteria from Office of higher education commission. This study compares each type of scoring between both institutes to evaluate effect size. The results show three scoring that the effect size more than 0.8 including Attitude score 2.293, Physical examination score 1.639,and total score effect size is 0.868 that reflected unequal of scoring and suggest to be grading each institute separately. Furthermore, after grading, the average grade of MSMC and PCMC group is 2.7968 and 2.7903 respectively. The effect size of grading is 0.0086. At the last, all individual student grades are calculated to compare with average 4th-year grade as the Pearson coefficient is 0.521. With this result, the grading of Otolaryngology is fairness and high correlation with their average 4th-year grade.
