So… I found out about this through a blog apparently promoting more controversy on the climate change issue, and I must say that it frustrated me in a profound way, and my rapid run through statistics this summer is not fast or in depth enough to really make me feel comfortable evaluating the conclusions.
This is where you all come in. I am becoming more versatile in statistics, but I was wondering if anyone could look at this with more knowledge of the statistical language going on here than I have. I’ll quote the findings and give you a link to the whole 4 page summary (though i would much rather find something more than the executive summary… I want to see the math that they’re complaining about).
In general, we found MBH98 and MBH99 to be somewhat obscure and incomplete and the criticisms of MM03/05a/05b to be valid and compelling. We also comment that they were attempting to draw attention to the discrepancies in MBH98 and MBH99, and not to do paleoclimatic temperature reconstruction. Normally, one would try to select a calibration dataset that is representative of the entire dataset. The 1902-1995 data is not fully appropriate for calibration and leads to a misuse in principal component analysis. However, the reasons for setting 1902-1995 as the calibration point presented in the narrative of MBH98 sounds reasonable, and the error may be easily overlooked by someone not trained in statistical methodology. We note that there is no evidence that Dr. Mann or any of the other authors in paleoclimatology studies have had significant interactions with mainstream statisticians.
In our further exploration of the social network of authorships in temperature reconstruction, we found that at least 43 authors have direct ties to Dr. Mann by virtue of coauthored papers with him. Our findings from this analysis suggest that authors in the area of paleoclimate studies are closely connected and thus ‘independent studies’ may not be as independent as they might appear on the surface. This committee does not believe that web logs are an appropriate forum for the scientific debate on this issue.
It is important to note the isolation of the paleoclimate community; even though they rely heavily on statistical methods they do not seem to be interacting with the statistical community. Additionally, we judge that the sharing of research materials, data and results was haphazardly and grudgingly done. In this case we judge that there was too much reliance on peer review, which was not necessarily independent. Moreover, the work has been sufficiently politicized that this community can hardly reassess their public positions without losing credibility. Overall, our committee believes that Mann’s assessments that the decade of the 1990s was the hottest decade of the millennium and that 1998 was the hottest year of the millennium cannot be supported by his analysis.”
This was taken from the Committee on Energy and Commerce’s website (where you can find the PDF of the summary of Wegmen’s findings).
It’s under the “Assessing Global Warming” section, and this is the press release for the hearing from this week.
This got no news coverage, and being something very in-committee, I find the whole thing very worrisome because while public opinion may be waking up, or paying more attention, policy is on its way to getting gutted.