Validity and Reliability of Auditory-Perceptual Scales for the Assessment of Stuttering Severity

Abstract

The current study investigated the appropriateness of equal appearing interval scaling, direct magnitude estimation scaling, and visual analog scaling for assessing stuttering severity by determining whether the continuum of stuttering severity, as defined in this study, was prothetic or metathetic. A secondary purpose was to determine interrater reliability of all three scaling methods. The stuttering severity of 20 reading samples was each judged by three groups of 15 listeners each who used the three scaling techniques. The results indicated that the sets of values were related to each other in a linear fashion, indicating that stuttering severity is a metathetic continuum, which is inconsistent with previous studies. These findings suggest that equal appearing interval scaling may be as appropriate as direct magnitude estimation or visual analog scaling for measuring stuttering severity. Future directions should include investigation of the effect of individual training on intrarater reliability and use of expert raters on construct validity and reliability.