The Construction of Keyforms for Obtaining Instantaneous Measures from the Occupational Performance History Interview Rating Scales

Abstract

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.