Application of rasch measurement to a measure of musical performance

This purpose of this paper is to describe the Rasch calibration of a portion of the Watkins-Farnum Performance Scale (WFPS), using a sample of 218 sixth graders from a middle school in Rhode Island. The WFPS is a test of instrumental music performance and consists of fourteen exercises of increasing difficulty, of which students play as many as possible until they fail two consecutive exercises. The WFPS has demonstrated reliability and validity. However, classical test theory did not allow its authors to calculate a measure of difficulty for each bar (because some students did not play all bars), or to allow judges the flexibility to shorten the scale (because of low reliability). Using Rasch scaling, item difficulties can be estimated, the test can be administered more efficiently, and perhaps most importantly, diagnostic information can be easily obtained.