Examination of the Scale Structure of the Moorong Self-Efficacy Scale: Application of Rasch Measurement theory

Abstract

<h3>Research Objectives</h3> To examine evidence of reproducibility, conceptual/content validation, and structural validity of Moorong Self-Efficacy Scale (MSES) by conducting an exploratory analysis applying the Rasch Measurement (RM) Model. <h3>Design</h3> Secondary RM analysis of data collected in a randomized controlled trial comparing two exercise interventions for persons living with spinal cord injury (SCI). <h3>Setting</h3> Community-dwelling persons living with SCI enrolled in an exercise study. <h3>Participants</h3> Persons (n=79) from the parent study had a traumatic SCI >3 months prior, injury level C5 to T12, age 18 years or older, and cognitive ability sufficient to follow instructions for exercise. Persons were excluded if they had uncontrolled hypertension or diabetes, pressure sores, movement-limiting shoulder pain, or participated in sports teams or organized exercise programs. <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> The MSES is a commonly used 16-item measure of self-efficacy for persons with SCI. Items are rated on a 7-point scale with 1=Very Uncertain and 7=Very Certain. <h3>Results</h3> We addressed item misfit, infrequent category endorsement, and category step disorder by removing two items and reorganizing the rating scale. Rating scale changes removed category 4 (Neutral), collapsed categories 1-3 (Very Uncertain, Somewhat Uncertain, and Uncertain) for all items, and further collapsed certainty categories for two items. Principal components analysis of the residual indicated a possible second dimension with a first-contrast Eigenvalue of 2.4. However, the contrasted item groups had explained variance < 10% and a dis-attenuated correlation=0.92 indicating they measure the same underlying trait. The small sample size precluded examination of differential item functioning. <h3>Conclusions</h3> Exploratory RM analysis of MSES produced a 14-item Rasch version (MSES-14R) which addresses measurement error inherent in the original MSES but is limited by small sample size. Further study should examine the item content and rating scale structure in context of the construct of self-efficacy for persons living with SCI. <h3>Author(s) Disclosures</h3> The authors have no financial or non-financial disclosures to make in regard to this oral presentation