Comparison of weighted and composite scores for pre-clinical dental learners

The weighted mean (WM) method for combining scores of assessment components can provide outcomes with biased reliability and score precision. The objective of this study was to compare the traditional WM with another method utilising the composite score (CS) principle for combining scores of a final summative assessment exercise for a pre-clinical dental course.

Data were collected from the final examination of third-year Preclinical Operative and Esthetic Dentistry course consisting of 3 parts: practical competency, objective structured practical examination and a written examination with weights of 33%, 17% and 50%, respectively. Scores from the 3 components were combined using the WM and CS methods. Weighted kappa was used to compare both approaches for agreement, and students' ranks were also compared.

Combining scores using CS scheme produced lower scores overall compared to WM with more apparent effect for the male group. Agreement between WM and CS was moderate (κ = 0.44) with major differences between students' ranks across the 2 modalities as only 21% of the cohort retained their ranks.

The CS method produced more reliable scores, resulting in moderate agreement with the WM and major shift in students' ranks. These findings necessitate further validity considerations before implementing the CS method and call for further studies that examine the consequences of composite measures in dental education.