Psychometric testing of the Icelandic Occupational Self-Assessment (OSA-IS)

Background The Occupational Self-Assessment (OSA) is a self-report measure of occupational competence and values used to identify goals and assess outcomes. The Icelandic version of the OSA (OSA-IS) has been through several developmental stages to evaluate its psychometric properties. Through each stage, revisions have been made. Aim To investigate the psychometric properties of the fourth revised version of OSA-IS. Materials and methods Retrospective data from 291 rehabilitation clients with a range of conditions were analysed using Rasch analysis of unidimensionality and descriptive statistics. All statistics were compared to established criteria. Results Analyses suggest the OSA-IS items define unidimensional constructs of occupational competence and values. Most (89%) participants completed the assessment in a reliable manner and no association was observed between demographic variables and fit status. Differences in the item hierarchies were observed between the original OSA and the OSA-IS, suggesting that Icelandic clients responded differently due to cultural, linguistic and/or sample differences. Conclusion and significance OSA-IS is a psychometrically sound instrument that may be used to support identification of client-centred goals and for intervention development. Clinicians should use score tables specifically developed for the OSA-IS to measure outcomes.