Test-retest reliability and cross validation of the functioning everyday with a wheelchair instrument.

The purpose of this study was to establish the test-retest reliability and content validity of an outcomes tool designed to measure the effectiveness of seating-mobility interventions on the functional performance of individuals who use wheelchairs or scooters as their primary seating-mobility device. The instrument, Functioning Everyday With a Wheelchair (FEW), is a questionnaire designed to measure perceived user function related to wheelchair/scooter use. Using consumer-generated items, FEW Beta Version 1.0 was developed and test-retest reliability was established. Cross-validation of FEW Beta Version 1.0 was then carried out with five samples of seating-mobility users to establish content validity. Based on the content validity study, FEW Version 2.0 was developed and administered to seating-mobility consumers to examine its test-retest reliability. FEW Beta Version 1.0 yielded an intraclass correlation coefficient (ICC) Model (3,k) of .92, p < .001, and the content validity results revealed that FEW Beta Version 1.0 captured 55% of seating-mobility goals reported by consumers across five samples. FEW Version 2.0 yielded ICC(3,k) = .86, p < .001, and captured 98.5% of consumers' seating-mobility goals. The cross-validation study identified new categories of seating-mobility goals for inclusion in FEW Version 2.0, and the content validity of FEW Version 2.0 was confirmed. FEW Beta Version 1.0 and FEW Version 2.0 were highly stable in their measurement of participants' seating-mobility goals over a 1-week interval.