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To ensure that researchers and practitioners make valid interpretations from children's self-reports, evidence must demonstrate that the self-report has appropriate psychometric properties. The Child Occupational Self Assessment (COSA) is a self-report of occupational competence and value for everyday activities designed to involve children in identifying goals and assessing outcomes. Five hundred two children with disabilities, ages 6-17, completed the COSA. We used a Rasch Partial Credit model and parametric and nonparametric statistics to obtain validity evidence. Evidence suggests that the COSA has good content, structural, and substantive validity as given by item and child fit statistics and unidimensionality evaluation. Evidence for external validity was mixed because child fit status and measures varied with some demographic and assessment administration variables. Evidence suggests that most children's responses to the COSA can be validly interpreted as indicators of occupational competence and value for everyday activities.
KEY WORDS
* activities of daily living
* disabled children
* psychometrics
* self assessment (psychology)
The field of occupational therapy has developed several self-report assessments for children and youths, including assessments of motor control competence (Missiuna, Pollock, & Law, 2004), participation in everyday activities (Keller, Kafkes, Basu, Federico, & Kielhofner, 2005; Law et al., 1998), and leisure activities (Henry, 2000; King et al., 2004). Researchers and practitioners can use these assessments to identify client concerns, develop meaningful goals for intervention, and generate client-reported outcomes. However, to use children's self-reports in practice with confidence, evidence must demonstrate that selfreports actually assess the concepts they propose to measure and that measurement of those concepts is consistent across practice contexts, administration methods, and children with different needs and abilities. This evidence supports the validity of interpretations made by practitioners and researchers on the basis of self-report responses.
The Child Occupational Self Assessment (COSA; Keller, Kafkes, Basu, et al., 2005) is a self-report of occupational competence and value for everyday activities. TheCOSAis based on concepts from the Model ofHumanOccupation(MOHO; Kielhofner, 2008) and measures the extent to which children feel they competently meet expectations and responsibilities associated with activities and the relative value of those activities. The process of completing the COSA also facilitates children's involvement in the therapy process. The administration manual directs practitioners to attend to those activities that the child feels less competent...