Rasch Analyses of the Wheelchair Use Confidence Scale for Power Wheelchair Users.

OBJECTIVES:To examine the dimensionality of the Wheelchair Use Confidence Scale for power wheelchair users (WheelCon-P), to identify items that do not fit the Rasch rating scale model as well as redundant items for elimination, and to determine the SEMs and reliability estimates for the entire range of measurements. DESIGN:Secondary analysis of cross-sectional data. SETTING:Community. PARTICIPANTS:Volunteer participants (N=189) using wheelchairs (mean age of the sample, 56.7±13.0y; mean years of wheelchair use experience, 20.4±16.4). INTERVENTIONS:Not applicable. MAIN OUTCOME MEASURES:59-Item WheelCon-P. RESULTS:Principal component analyses confirmed the presence of 2 self-efficacy dimensions: mobility and social situation. Eleven mobility items and 5 social situation items fit the Rasch rating scale model. Three items misfit the model using all 16 items (ie, WheelCon-P short form). In each of the mobility, social situation, and WheelCon-P short form range of measurements, the 2 lowest and 2 highest measures had internal consistency reliability estimates below .70; all other measures had reliability estimates above .70. CONCLUSIONS:The WheelCon-P is composed of 2 self-efficacy dimensions related to mobility and social situations. The scores from the WheelCon-P short form and the 11-item mobility and 5-item social situation dimensions using a 0 to 10 response scale have good reliability.