Stuttering Severity Instrument - Fourth Edition (SSI-4) by Glyndon D. Riley The Fourth Edition of this enduring test continues to provide a reliable measure of stuttering severity--now with updated norms, quicker administration, and computer scoring. Appropriate for anyone over the age of 2 years and 10 months, the SSI-4 is an excellent way to quantify stuttering problems and evaluate the effectiveness of therapy. Administration instructions differ slightly for readers and nonreaders, but in each case, speaking samples are evaluated according to specific criteria: Frequency Expressed as percentage of syllables stuttered and converted to scale scores ranging from 2 to 18   Duration Average length of the three longest stuttering events, timed to the nearest tenth of a second and converted to scale scores ranging from 2 to 18   Physical Concomitants Distracting sounds, facial grimaces, head movements, and arm and leg movements, expressed as scale scores ranging from 0 to 20   Naturalness of Speech Norms, presented separately for various age groups, are based on a sample of 72 preschool children, 139 school-aged children, and 60 adults. Individually administered in just 15 to 20 minutes, the SSI-4 is well suited to both clinical and research use.