WISC-III index score profiles of 520 Swedish children with pervasive developmental disorders.

WISC-III (Wechsler, 1991) index score profiles and their characteristics were examined with traditional statistics in a large Swedish sample consisting of children with autistic disorder (n = 85), Asperger's disorder (n = 341), or pervasive developmental disorders not otherwise specified (PDD-NOS; n = 94). There was a clear and significant difference in level between children with Asperger's disorder, who performed in the average range according to the Swedish standardization, and children with either autistic disorder or PDD-NOS, who performed below the average range (almost 2 standard deviations below the mean), but few other differences between the diagnostic groups were found. The variation in this sample, compared with the Swedish standardization, was generally larger in regard to the size of standard deviations and to the proportion of individuals who exhibited significant differences between indices. The result implied that a WISC-III profile could not be used to discriminate between the different PDDs.