Children with autism benefit from routines and structure

The recent post from CEC Smartbrief discusses the benefits of schedules and structures for children with autism. http://r.smartbrief.com/resp/cSlHCcbSmRBZdrxvCidafOCicNRuTn?format=standard

What is Autism?

There are many technical definitions associated with the term autism such as autism spectrum disorder or pervasive developmental disorder. Essentially, autism is a general term of one type of disorder on a spectrum.  Children with this diagnosis do not all exhibit the same behaviors and therefore make it difficult to even diagnose the disorder.  For more information about autism please click on the link http://www.autismspeaks.org/.

Why do you think autism is so hard to define if there is already research out there?