A Comparison of 100-Point Numeric Grading System and Letter-Based Grading System in Medical Clerkship Assessment: A Single-Centre Study

Abstract

Background: Assessing medical students’ performance during clerkship remains a significant challenge due to the lack of commonly accepted standards. The purpose of this study is to provide a comparative analyse of the validity and reliability of a 100-point numeric grading system and a simplified letter-based grading system in clerkship assessment. Methods: A total of 176 medical students were enrolled in this study. Among them, 80 students (enrolment years 2015–2017) were assessed using the 100-point system, while 96 students (enrolment years 2018–2020) were assessed using the letter-based system. Grade Point Averages were computed from the scores of each core clerkship program rotations for comparison. Internal consistency was measured using Cronbach's α, and the Pearson’s correlation test was used to assess the correlation between pre- and post-clerkship academic scores. Results: The distribution of grades between the two grading systems differed significantly. The 100-point numeric grading is much more skewed, showed very high internal reliability (Cronbach's α = 0.886) but poor external validity (Pearson’s test, p > 0.05). The letter-based grading system demonstrated acceptable internal reliability (Cronbach's α = 0.553) and good external validity (Pearson’s test, p < 0.001), Conclusion: This study demonstrated that the letter-based grading system was more effective for assessing medical students' performance during clerkship than the conventional 100-point numeric grading system.