The Stereotyped Behavior Scale for adolescents and adults with mental retardation.

The development of the Stereotyped Behavior Scale for adolescents and adults with mental retardation was described. Service provider staff in three states selected 600 clients known for stereotypic behaviors and then used 66 items to rate the frequency of occurrence of these behaviors. Items with test-retest reliability less than .45 and/or interrater agreement less than .30 were deleted. The remaining 30 items were subjected to a principal component analysis with varimax rotation. A single-factor solution emerged, which explained 24.9% of the variance. After eliminating 4 items with low factor loadings, we found that the final 26-item Stereotyped Behavior Scale had an internal consistency alpha of .88, test-retest reliability was pI = .90, and interrater reliability was pI = .76.