Assessment of Psychometric Properties of an Oral Health Care Measure of Cultural Competence Among Dental Students Using Rasch Partial Credit Model

Reliability, validity, and feasibility of the only validated oral health care measure of cultural competence, the Knowledge, Efficacy, and Practices Instrument (KEPI), have been confirmed. However, the instrument’s psychometric properties including item and person reliability, category response functioning, and scale targeting, as well as differential scale functioning for subgroups, have not yet been examined. The aim of this study was to test the psychometric properties of KEPI among dental students using Rasch Partial Credit Model to determine if this model provided broader valid information that cannot be demonstrated according to Classical Test Theory. A total 1,290 dental students in the first or final semester at four U.S. dental schools were invited to participate in the study in 2016. Of those, 1,231 individuals completed the survey, for a 95.4% response rate. The participants were 613 males and 618 females and 889 non-underrepresented minority (URM) and 342 URM students. The Rasch Partial Credit Model assessed the psychometric properties of KEPI’s 20 items/three subscales. Differential scale functioning was found in the Culture-Centered Practice and Efficacy of Assessment subscales. Four items were endorsed differentially by gender; four items were endorsed differentially by URM/non-URM students. This study examined the psychometric properties of the KEPI using Rasch analysis to assess differential item functioning by dental student gender and race. The results provided valid evidence for the high internal reliability, measurement properties, and unidimensionality for the KEPI domains, ideal targeting, and well response category functioning, showing that the KEPI is a reliable instrument for measuring the subscales Knowledge of Diversity, Culture-Centered Practice skills, and Efficacy of Assessment for health care providers.