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There is a saying, “the devil is in the details…”Â
Assessment of autism with the ADOS is fraught with difficulties. The ADOS per the Manual does not assess for Category 3 behaviors — repetitive, stereotypic behaviors.Â
 There must be substantial Category 3 behaviors for a DSM-IV-TR diagnosis. It sounds like, per Assessment of Autism Spectrum Disorders (2009) that a new algorithm published in 2007 takes care of the problem. But does it?Â
Which algorithm makes a significant difference. What algorithm do psychologists use when using the ADOS to assess for autism? The one in the manual or the one published later  in 2007? If someone buys an ADOS in 2010 are they given instructions to use the 2007 algorithm or the one in the Manual?Â
The following is from  Assessment of Autistic Spectrum Disorders, pg. 65:Â
“The ADOS uses cutoff scores for two separate domains (Social Interaction and Communication) as well as a Communication-Social Interaction total cut-off score, in order to make the diagnostic distinction between autism and the broader category of ASD.Â
“Although the ADOS has many similarities to the DSM -IV-TR and International Classification of Diseases… models of diagnosing ASD, the ADOS algorithm included in the manual does not include a measure of restricted, repetitive and stereotyped patterns of behavior ...In addition the ADOS does not include information about the age of onset or early history required for a DSM-IV-TR or ICD-10 diagnosis.Â
“Recently, however, new algorithms for the ADOS have been published (Gortham, Risi, Pickles & Lord, 2007 that do includerestricted/repetitive/stereotyped behaviors and no longer have separate Social Interaction and Communication domains…”
So, are the authors of Assessment of Autism Spectrum Disorders (2009) suggesting that the new algorithm should be used? Are psychologists using the ADOS using the Manual or the new algorithm? Â
Where to find the algorithm:Â
Gotham, K., Risi, S., Pickles, A., & Lord, C. (2007). The Autism Diagnostic Observations Schedule: Revided Algorithms for Improved Diagnostic Validity. Journal of Autism & Developmental Disorders, 37 (4), 613-62