Table 1.

Published cluster analyses on persons with autism spectrum disorders

Primary author	Year published	Sample size and age	Sample diagnoses	Primary independent variables	Clusters identified	Cluster descriptions
Siegel	1986	n = 46 4–20 years, M = 10.7 years	AD	Developmental history questionnaire, parent report of current behavior, behaviors coded from a videotaped diagnostic evaluation	4	Classic autism Severe intellectual disability Schizotypal personality traits Anxious/negativistic behaviors
Eaves	1994	n = 166 3–12 years, M = 7.1 years	AD, ASD, ASP, AT, HFA	Behaviors coded retrospectively from hospital charts	4	Typically autistic Low-functioning autism High-functioning autism Hard-to-diagnose autism
Sevin	1995	n = 34 2–22 years, M = 7.7 years	AD, ASD	Childhood autism rating scale, autism behavior checklist, ritvo-Freeman real life rating scale, Vineland adaptive behavior scales	4	Severe autism Moderate autism Mild autism High-functioning autism
Prior	1998	n = 135 3–21 years, M = 10.22 years	AD, ASD, HFA (only high functioning children included)	Autistic disorders checklist, peabody picture vocabulary test	3	Autism ASD Mild ASD
Fein	1999	n = 194 3–7 years, M = 4.9 for ASD	ASD, Developmental Language Disorder, low IQ	Autistic disorders checklist, peabody picture vocabulary test, Vineland adaptive behavior scales	2	Low-functioning autism High-functioning autism
Stevens	2000	n = 138 7–9 years, M = 8.6 years	ASD	Autistic disorders checklist, peabody picture vocabulary test, Vineland adaptive behavior scales	2	Low-functioning autism High-functioning autism

AD autistic disorder, including infantile autism and residual state autism, ASD autism spectrum disorder or pervasive developmental disorder, ASP Asperger’s syndrome, AT autistic tendencies, HFA high functioning autism