DEVELOPMENT AND VALIDATION OF THE VISUAL REPRESENTATIONS TEST IN CHEMISTRY FOR PRE-MEDICAL STUDENTS
DEVELOPMENT AND VALIDATION OF THE VISUAL REPRESENTATIONS TEST IN CHEMISTRY FOR PRE-MEDICAL STUDENTS

Summary/Abstract: The ability of pre-medical students to use visual representations in chemistry is crucial in understanding complex and abstract chemistry concepts. To measure students’ knowledge and understanding of visual representations in chemistry, this study developed and validated the Visual Representations Test in Chemistry (VRTC). A hypothesized three-level progression of this construct was drafted and validated using Rasch analysis. The first version of the VRTC comprised 26 multiple-choice items covering particle models, ball-and-stick models, skeletal structures, electrostatic potential maps, Fischer projections, and Newman projections. The test was administered to 827 pre-medical students across four institutions in the Philippines. Dichotomous Rasch analysis provided evidence of reliability, unidimensionality, and item fit. Item-content validity indices indicated fair-to-excellent values, and the item hierarchy confirmed the hypothesized progression of knowledge about visual representations in chemistry. Analysis of variance of item difficulties revealed significant differences in mean item difficulty across the three hypothesized levels of knowledge, F(2,23) = 17.273, p<.001, supporting construct validity. However, Rasch analysis revealed student ability gaps, items with overlapping difficulty levels, and differential item functioning based on year level. Overall, the VRTC exhibited adequate psychometric properties for assessing pre-medical students’ knowledge and understanding of visual representations in chemistry.

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