Criterion-related and construct validity of the pervasive developmental disorders rating scale and the autism behavior checklist

This study investigated the validity of the Autism Behavior Checklist (ABC; Krug, Arick, & Almond, 1993) and the Pervasive Developmental Disorders Rat ing Scale (PDDRS; Eaves, 1993a). Both instruments are screening devices des igned to measure characteristics of individuals with autistic disorder or, more broadly, pervasive developmental disorders. Results showed that the to tal scores of the ABC and PDDRS measure significantly overlapping construct s (r = .80). Further, both instruments significantly discriminated between participants with autistic disorder and children with diagnoses frequently confused with autistic disorder. Both instruments provided re spectable ind ices for classification accuracy (PDDRS overall accuracy = 88%, ABC overall accuracy = 80%). Finally, the ABC and PDDRS agreed in their classification s of 85% of the 136 participants; a phi coefficient based on the instrument s' nominal classifications of the participants equaled .68 (p < .001). (C) 2000 John Wiley & Sons, Inc.