Abstract
PURPOSE: This study evaluated the underlying subdomain structure of the Self-Directed Learning Readiness Scale (SDLRS) for medical students and refined the instrument to measure the subdomains to provide evidence for construct validity. Developing self-directed learners is a well-recognized goal amongst medical educators. The SDLRS has been frequently used, however, lack of construct validity makes it difficult to interpret results. METHODS: To identify the valid subdomains of the SDLRS, items were calibrated with the graded response model (GRM) and results were used to construct a 30-item short form. Short-form validity was evaluated by examining the correspondence between the total scores from the short form and the original instrument for individual students. RESULTS: A five-subdomain model explained the SDLRS item response data reasonably well. These included: (1) initiative and independence in learning, (2) self-concept as an effective learner, (3) openness to learning opportunity, (4) love of learning, and (5) acceptance for one's own learning. The unidimensional GRM for each subdomain fits the data better than multi-dimensional models. The total scores from the refined short form and the original form were correlated at 0.98 and the mean difference was 1.33, providing evidence for validation. Nearly 91% of 179 respondents were accurately classified within the low, average, and high readiness groups. CONCLUSION: Sufficient evidence was obtained for the validity and reliability of the refined 30-item short-form targeting five subdomains to measure medical students' readiness to engage in self-directed learning.