The Occupational Self Assessment (OSA) was designed to guide collaborative treatment planning and measure client-reported change to document therapy outcomes. This study examined the stability of the OSA and its ability to detect changes in reported Competence and Values. The OSA was administered twice to 112 participants with disabilities 58 to 650 days apart. A Rasch rating scale model was used to analyze the data and determine the stability. Competence and Values items were stable over time. The Competence rating scale was used by participants in the same manner at both administrations. However, the Values rating scale was used differently at time 2; participants were less likely to use the Values rating scale category “More important” at time 2. Thirty-two percent and 49% of participants had significantly different measures at time 2 on Competence and Values scales, respectively. This study lends support for the use of the OSA as a client-reported outcome measure.

Occupational therapists routinely use rating scales to indicate a client's level of functioning, monitor progress, and evaluate intervention success. Rating scales yield ordinal data, whereas true measurement requires interval level data. Rasch analysis can convert rating scale data into true interval measures, but the use of measures derived from this method is limited in everyday occupational therapy practice because raw data must be computer scored. The keyform is an alternative to computer scoring. It is a paper-and-pencil form with which the therapist can record and convert ratings to interval measures while exercising intuitive quality control of the data. This article illustrates the application of this methodology to the Occupational Performance History Interview-2nd Version (OPHI-II). The authors discuss the OPHI-II scales, describe the methodology for developing the keyforms, and demonstrate how they are used.

No abstract