Mark Blaxill on autism and Brick Township, NJ.

[proverbialwisdom]

6. Mark Blaxill writes, "For some, myself included, a picture is worth a thousand words."

http://www.ageofautism.com/2014/03/awaiting-autism-prevalence-numbers-what-did-the-cdc-know-and-when-did-they-know-it.html

By Mark Blaxill
March 27, 2014 (originally published in 2009)

FULL TEXT at link.

In mid 2002, it occurred to a few of us at SafeMinds that the CDC's conclusion in their Brick Township report was likely to be flawed. Not only was the rising trend apparent in their data, there were also a number of odd elements in their design and write up. For one thing, the age groupings were strange—separating the sample into two groups of unequal size, 3-5 and 6-10 year olds. Why would they not divide the population into equal sizes, putting 3-6 year olds and 7-10 year olds together? For another, as I had learned in examining Lisa Croen's claims of diagnostic substitution in California, autism time trends can be easily misinterpreted if the analysts don't factor in the lag time that the youngest children face in getting recognized (the technical term is "ascertainment bias&quot . What if the Brick team, as most survey teams had done before them, had simply undercounted three year olds?

So Sallie Bernard sent an email to Frank DeStefano of the CDC, whom she had met at a recent meeting. She asked him what would happen to the Brick rates with 3 year olds removed. And he responded in a May 10, 2002 email, "For overall ASD, the prevaleces (sic) were: 10.2 per 1,000 among children 4-6 years old, 4.4 per 1,000 among those 7-10 years old." Sallie promptly thanked him and, noticing that this rate differential seemed larger than the published study, asked him if these were statistically significant. DeStefano's response was telling.

"The results are based on 35 cases out of an estimated 3442 children 4-6 years of age, and 19 cases out of an estimated 4272 children 7-10 years of age. The difference in prevalences noted below is statistically significant." [emphasis added]

In other words the published conclusion changed completely if you simply removed a single age group, the three year olds.

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For some, myself included, a picture is worth a thousand words. And if the problem in Brick was indeed more than a cluster, if there was a broader national trend towards rising autism rates, then what matters is not just the age of the Brick children, but their birth years. A more consistent national trend would be revealed if we could find similar changes in autism rates in the same birth years. And a clear picture of the increasing trend would help us identify the kinds of environmental causes that weren't just local elevated toxins in the Brick water supply.

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