Severe problem behaviors such as self-injury and aggression are frequently observed in young children under age 5 with intellectual and developmental disabilities (IDD). Although early identification of problem behavior is critical to effective intervention, there are few standardized measures available that identify severe problem behavior in…

The Autism Spectrum Quotient (AQ) has been widely used for measuring autistic characteristics in parents of children with autism spectrum disorders (ASD). Nonetheless, its psychometric validity is yet to be justified. This study tested the factor structure of the AQ by means of principal component analysis and confirmatory factor analysis using,…