Item development, internal consistency, and known-groups validity of the Self-Directed Mobility Scale

Purpose: The aims of the current study include to: (1) describe the item development; and (2) begin the process of establishing the internal consistency and known-groups validity of the Self-Directed Mobility Scale. The purpose of the scale is to assess paediatric physical and occupational therapists' views towards self-directed mobility and their perceived ability and intentions to advocate for children's access to self-directed mobility. Methods: Three individuals with expertise in kinesiology, psychology, paediatric rehabilitation, and disability studies served as the expert panel for item development. Four samples were included to determine internal consistency and known-groups validity: 350 physical therapists, 89 occupational therapists, 279 kinesiology undergraduate students, and 528 health and wellness undergraduate students. Results: The internal consistency was above the acceptable level of 0.70 (range = 0.72-0.77) for all samples when two items regarding promoting other motor skills prior to powered mobility use and the temporary use of a mobility device were removed. Known-groups validity was established between all samples. Conclusions: The Self-Directed Mobility Scale appears to be a valid tool for assessing views of self-directed mobility and mobility advocacy intentions in paediatric physical and occupational therapists, as well as undergraduate students. Future work should examine the internal consistency based on study sample to ensure the (> 0.70) acceptable Cronbach's alpha level is met.