Content validity of the relative mastery measurement scale: A measure of occupational adaptation

This research addressed the need for a clinically practical and psychometrically sound measure of a central construct of Occupational Adaptation theory. As an indicator of Occupational Adaptation, the Relative Mastery Measurement Scale (RMMS) was developed and evaluated for content and construct validity. The RMMS assesses individuals' perceptions of their effectiveness, efficiency, and satisfaction regarding their responses to occupational challenges. In the first phase, the content validity of the RMMS was statistically evaluated using the ratings of five experts in Occupational Adaptation. Lu's Coefficient of Agreement among the experts for the final 12-item RMMS was an acceptable .95. In phase two, construct validity and reliability were examined using a combination of Rasch analysis and traditional measurement statistics. Participants were 150 rehabilitation clients. Reliability and validity was supported through the unidimensionality of 11 of 12 RMMS items by the ordering of item difficulty, goodness-of-fit statistics, factor analysis, and point-biserial correlations