"Assuming you have an autistic child or relative, your personal experience does not constitute the research necessary to learn whether the incidence is growing or stable. I can assure you that in the early 70s when I was in graduate school, the diagnosis was common enough that every small town had several children in treatment."
Actually, I have 3 autistic children (pretty sure i shared that in a previous post?). My experience that you dismiss so easily comes partly from dealing with the doctors and school district in my small town for the last 19 years, and from parenting autistic children for those same 19 years. I can also assure you that autism is not viewed, diagnosed or treated the same way it was in the '70s.
I am not dismissing your experience, but your experience is not sufficient to determine if there is an increase in the occurrance of autism. The article is very clear about the problems encountered in trying to obtain statistics.