Reliability and Similarity of the Stuttering Severity Instrument-Fourth Edition and a Global Severity Rating Scale

Abstract

ABSTRACT Purpose: The present study compared reliability and similarity for two measures of stuttering severity: The Stuttering Severity Instrument – Fourth Edition (SSI-4) Final Severity Rating and a 5-point global severity rating (GSR) scale. Method: Twenty-four graduate students rated four videos of persons who stutter using either the SSI-4 procedures or a 5-point GSR scale. Intra-rater and inter-rater agreement values, and obtained severity ratings, were compared across the two methods. Results: The SSI-4 produced better intra-rater and inter-rater agreement, although neither measure produced an acceptable level of inter-rater agreement of 80%. Severity scores produced from the GSR scale were significantly higher compared to the SSI-4 Final Severity Ratings. Conclusions: The 5-point GSR scale used in the present study is not a sufficient replacement for the SSI-4 as a measure of stuttering severity. Rater agreement for both methods may benefit from training and the use of exemplars to standardized levels of stuttering severity.