Tuesday, April 25, 2006

Curious Errors in Earlier Geier Paper

In light of the Geier & Geier (2006) debacle, I’ve reviewed earlier autism papers by these same authors in order to determine if similarly significant errors can be found. Let me introduce a paper titled "A comparative evaluation of the effects of MMR immunization and mercury doses from thimerosal-containing childhood vaccines on the population prevalence of autism" (Geier & Geier, 2004). The conclusions of this paper cannot be sustained any longer, of course, but I would like to bring the reader’s attention to the pattern of errors found in Geier & Geier (2004).

Prevalence By Birth Year Cohort

The paper claims to show that there is a correlation between the thimerosal dose per child and the “prevalence of autism from the late 1980s to the mid-1990s.” Upon closer examination, this is not what the paper shows at all. The paper finds a dubious correlation of thimerosal dose per child and the administrative prevalence of autism by birth year cohort. This is a non-trivial difference as I will explain.

The first sign that something is wrong is the prevalence line in Figure 2 of the paper, which shows a downward trend in prevalence starting in 1994 and continuing through 1996. As we all know, there was no decline in the prevalence of autism during those years, in any age cohort. The problem is that the authors use an autism prevalence line that always has a downward pattern in recent years (a hook shape if you will) as illustrated by the following figure.



This is because autistic children are seldom diagnosed before the age of 18 months, some “regress” some time after that, and there must also be a late diagnosis factor. This is why this prevalence line keeps changing as the report is updated year after year.

The authors should have analyzed the prevalence trend of an age cohort, e.g. the 3-5 cohort. Instead, they attempted to draw conclusions from differences in the prevalence of autism in different age cohorts (birth year cohorts), which is clearly an invalid analysis. I challenge the authors to demonstrate a correlation using autism prevalence in the vaccination age cohort.

In the figure above, the blue line (2002) is perhaps the one that happens to be the best fit for the mercury dose graph in Figure 2 of the paper. The authors produce their own trend line using the DOE Annual Report to Congress for the 2001-2002 school year, and the CDC’s yearly live birth data. (The latter is also used to calculate the dose of thimerosal per child).

The trend line the authors chose (perhaps coincidentally) is a much better fit than any of the trend lines from the figure above. I challenge the authors to demonstrate the correlation holds using prevalence data by birth year cohort from the most recent report available.

Omission of 1986-1989

Table 1 as well as Figure 2 of the paper omit data for the 4 year range 1986 to 1989. This, of course, is not the proper way to do an annual graph, even if data is unavailable for those years. It is unclear if the authors are aware that if data for those years had been included, it would likely be much more difficult to argue that Figure 2 illustrates a pattern of correlation. Additionally, there would likely be several dots outside of the trend line in Figure 1.

It is possible this error of omission is unintentional. The authors state they “selected birth cohorts that had complete information from all the necessary sources.” Regardless, I challenge the authors to obtain the data for the missing years and produce new versions of Figure 1 and Figure 2.

Conclusion

Geier & Geier (2004) contains significant flaws, the pattern of which warrants further investigation. I will send a short note to Medical Science Monitor with a reference to this post. A full retraction appears necessary in this case but is not expected, based on prior experience with similarly invalid papers.

9 comments:

  1. Keep going Joseph - you're doing sterling work taking these shysters down.

    ReplyDelete
  2. Curiouser and curiouser. I predict their claims of persecution will increase steadily along with population growth.

    ReplyDelete
  3. David Geier is president of MedCon Inc.

    I'm just saying...

    June 5, 2005

    "Now for the good news -- I just wish there was more of it for you who already have children with autism," said Mark Geier. "The number of autism occurrences is actually starting to go down, now that thimerosal has been taken out of some vaccines."


    Currently, the Geiers are conducting research with children using testosterone reducing drugs, as their research claims children with autism have higher levels of the hormone and experience premature sexual development at ages as young as three and four.

    ReplyDelete
  4. David Geier is president of MedCon Inc.

    Yeah, a bit of an unfortunate name choice :)

    ReplyDelete
  5. Just FYI, the technical term for the phenomenon that causes the "hook" in the birth-year-cohort prevalences is "left censorship." There are various specialized statistical methods for dealing with left-censored data; many of them were developed in the context of analyzing environmental contamination (where the level of a contaminant can't be accurately quantified below a test's detection limit, but can't be treated as zero either). Treating left-censored observations (such as kids too young to be properly evaluated for autism) as if they had definite values is a no-no.

    Also, once again we see the Geier's penchant for using OLS regression on time-series data, a sign of amateurism at best.

    ReplyDelete
  6. Ebohlman,

    Thanks for your clarification.

    a sign of amateurism at best.

    At this point I'm concerned we're looking at more than this.

    ReplyDelete
  7. The Geiers aren't idiots or amateurs. I'm becoming more convinced that they're intentional schysters who are intentionally putting out shoddy (or outright fradulent) research for the purposes of buttressing thimerosal-related lawsuits.

    ReplyDelete
  8. And this was Mark Geier in history:

    http://briandeer.com/wakefield/dtp-garth.htm

    Nobody can say he hasn't been consistent.

    ReplyDelete
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