The last time I posted, I looked into David Kirby's claims about drops in some IDEA numbers and I noted that there were discrepancies in the numbers reported by David Kirby compared to the only source he cited. I posted a request for clarification at HuffingtonPost.com, but my message was never approved apparently. I will try that again, adding a reference to this post.
On January 20, David Kirby reported (in EOHarm) that he scanned the IDEA data for drops in the autism category between 2004 and 2005. He found 4 states that show drops in the 3-5 administrative prevalence of autism between those two years: Hawaii, Iowa, Louisiana and Vermont. He adds:
The declines are modest, but noticeable, and the first ever decline in actual numbers that has ever been reported, as far as I can tell.
Well, he could not tell very far apparently. I went ahead and looked at state by state data between 2000 and 2005. After a quick glance at data for these four states only, I can see there was a big drop in the Iowa 3-5 caseload between 2000 and 2001; one in Louisiana between 2002 and 2003; and one in Vermont between 2002 and 2003. I am sure other drops can be found in other states, particularly those with small autism caseloads. David Kirby might have been close to realizing that when he said the following:
These four states have little in common and a from 4 completely different regions. The only trait they share is a relatively modest population rate. I don't know if that matters or not.
You see, the 3-5 caseload in California does not show any big fluctuations because California has thousands of children in that cohort. The four states Kirby found have less than 200 autistic children in that cohort. Fluctuations are expected statistically. I made a graph of caseload in these four states for 3 year olds only. Fluctuations are more obvious in that narrower cohort, but I chose 3 year olds because that would be the most telling cohort in terms of a drop in thimerosal exposure.
When you look at that graph, keep in mind that this is not a representative sample of states. This is a graph of four states handpicked by David Kirby based on whether their 3-5 prevalence has dropped between 2004 and 2005.