Tag Archives: hockey stick

GMU contradictory decisions on Wegman: Plagiarism in CSDA, but not in 2006 congressional report

[Updates, Feb. 23-24: I have added extensive discussion “below the fold”, starting with the section entitled GMU Process. The summary has been updated with additional links to side-by-side comparisons  to enable readers to make their own judgments.]

Dan Vergano of USA Today reports on an “all faculty” announcement from George Mason University concerning the outcome of two faculty committee  investigations of plagiarism charges against GMU statistics professor Edward Wegman.

One investigation concerned a 20o8 article by Wegman protege Yasmin Said, Wegman himself and two others in Computational Statistics & Data Analysis (CSDA). The committee upheld CSDAs previous plagiarism finding; as “team leader”, Wegman was found to bear responsibility and has been asked to retract the article and apologize to CSDA’s editor. GMU has also issued an official letter of reprimand confirming that finding of research misconduct.

A separate GMU committee investigated the 2006 congressional report commonly known as the Wegman Report, a critique of the Mann-Bradley-Hughes “hockey stick” reconstruction. That investigation held that “no scientific misconduct was involved”,  only “extensive paraphrasing of another work” that was “referenced repeatedly”.  [That finding holds that there was no plagiarism in Wegman Report background material derived from Raymond Bradley’s Paleoclimatolgy; readers may judge side-by-side comparisons of the passages on tree-rings and ice core and coral proxies for themselves].  However, in a bizarre twist, it appears that the committee did not even consider side-by-side comparison of the Wegman Report’s long and unreferenced background section on social network analysis, part of which was reused in the later CSDA article and gave rise to the plagiarism finding in the other GMU case!

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Replication and due diligence, Wegman style

By Deep Climate

Today I continue my examination of the key analysis section of the Wegman report on the Mann et al “hockey stick” temperature reconstruction, which uncritically rehashed Steve McIntyre and Ross McKitrick’s purported demonstration of the extreme biasing effect of Mann et al’s “short-centered” principal component analysis.

First, I’ll fill in some much needed context as an antidote to McIntyre and McKitrick’s misleading focus on Mann et al’s use of principal components analysis (PCA) in data preprocessing of tree-ring proxy networks. Their problematic analysis was compounded by Wegman et al’s refusal to even consider all subsequent peer reviewed commentary – commentary that clearly demonstrated that correction of Mann et al’s “short-centered” PCA had minimal impact on the overall reconstruction.

Next, I’ll look at Wegman et al’s “reproduction” of McIntyre and McKitrick’s  simulation of Mann et al’s PCA methodology, published in the pair’s 2005 Geophysical Research Letters article, Hockey sticks, principal components, and spurious significance).  It turns out that the sample leading principal components (PC1s) shown in two key Wegman et al figures were in fact rendered directly from McIntyre and McKitrick’s original archive of simulated “hockey stick” PC1s. Even worse, though, is the astonishing fact that this special collection of “hockey sticks”  is not even  a random sample of the 10,000 pseudo-proxy PC1s originally produced in the GRL study. Rather it expressly contains the very  top 100 – one percent – having the most pronounced upward blade. Thus, McIntyre and McKitrick’s original Fig 1-1, mechanically reproduced by Wegman et al, shows a carefully selected “sample” from the top 1% of simulated  “hockey sticks”. And Wegman’s Fig 4-4, which falsely claimed to show “hockey sticks” mined from low-order, low-autocorrelation “red noise”, contains another 12 from that same 1%!

Finally, I’ll return to the central claim of Wegman et al – that McIntyre and McKitrick had shown that Michael Mann’s “short-centred” principal component analysis would mine “hockey sticks”, even from low-order, low-correlation “red noise” proxies . But both the source code and the hard-wired “hockey stick” figures clearly confirm what physicist David Ritson pointed out more than four years ago, namely that McIntyre and McKitrick’s “compelling” result was in fact based on a highly questionable procedure that generated null proxies with very high auto-correlation and persistence. All these facts are clear from even a cursory examination of McIntyre’s source code, demonstrating once and for all the incompetence and lack of due diligence exhibited by the Wegman report authors.

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Wegman Report update, part 1: More dubious scholarship in full colour

This is the final instalment in a series of posts documenting dubious scholarship and unattributed sources in the background chapter of the touchstone of climate contrarians known as the Wegman Report. That report has been touted as Exhibit A proving the “destruction” of Michael Mann’s “hockey stick” graph by self-styled climate auditor Steve McIntyre.

Previously, I found extensive passages bearing “striking similarity” to a classic text by the distinguished paleoclimatologist (and “hockey stick” co-author) Raymond Bradley in the background sections on tree rings and on ice cores. Subsequently, the background section on social networks was found to contain material apparently drawn without attribution from a variety of sources, including Wikipedia and several text books.

This time, I’m looking at section 2.2 (see Wegman Report PDF at p. 15), which gives the background of key statistical concepts, including Principal Component Analysis. Astonishingly, even this section appears to contain a significant amount of unattributed material from other sources, although quite a bit less than the other sections. Again, Wikipedia appears to be a key source, along with a couple of text books.

I’ll also introduce some refinements to the text analysis, based largely on John Mashey’s recent innovations. Those refinements allow a better characterization of the relationship between various passages in Wegman et al and their apparent antecedents, as well as permitting a quantitative analysis based on word counts.

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Terence Corcoran whopper: Mann’s hockey stick “eliminated some of the data from 1960 forward … and then spliced on actual temperature data”

Terence Corcoran may well have just unleashed the National Post’s biggest whopper yet about climate science – and that’s saying something.

Corcoran’s commentary on the recent Russell “climategate” email review lays one error-laden defamation on top of another, as he attempts to demonstrate that the report “provides plenty of evidence that climate science has been and remains an uncertain shambles”. Oh, and apparently the review “portrays climate science as a field filled with uncertainty, debate, lack of openness, data hoarding and ill-will.”

Along the way, Corcoran even manages to confuse a little known Phil Jones graphic with Michael Mann’s “hockey stick” millenial temperature reconstruction. This leads to the astonishing (and entirely wrong) accusation that the hockey stick creators “eliminated some of the data from 1960 forward … and then spliced on actual temperature data”. Yet neither the “hockey stick” graph (the real one) nor the associated Mann et al study are mentioned in the report at all!

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Wegman and Said on social networks: More dubious scholarship

Today I continue my exploration of the dubious scholarship in the contrarian touchstone known as the Wegman report, this time focusing on the report’s background section on social network analysis. As many readers may recall, Wegman et al used a simplistic analysis of co-author relationships to speculate about supposed lack of independence between researchers in paleoclimatology, accompanied by lapses of rigour in the peer review process. This, of course, echoed similar accusations by self-styled climate auditor Steve McIntyre.

In both the original Wegman report and a subsequent follow-up paper by Yasmin Said, Wegman and two others, the background sections on social network research show clear and compelling instances of apparent plagiarism. The three main sources, used almost verbatim and without attribution, have now been identified. These include a Wikipedia article and a classic sociology text book by Wasserman and Faust. But the papers rely even more on the third source, a hands-on text book that explores social network concepts via the Pajek analysis software package – the same tool used by the Wegman team to analyze “hockey stick” author Michael Mann’s co-author network.

Not only that, but the later Said et al paper acknowledges support from the National Institutes on Alcohol Abuse and Alcoholism, as well as the Army Research Laboratory, raising a host of new issues and questions. And chief among those questions is this: Will George Mason University now finally do the right thing and launch a complete investigation of the actions and scholarship of Wegman and Said?

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Wegman (and Rapp) on tree rings: A divergence problem (part 1)


Edward Wegman


There has been renewed interest in the Wegman Report, which purported to critique the work of paleoclimatolgists Michael Mann, Raymond Bradley and Malcolm Hughes and their controversial “hockey stick” millennial temperature reconstruction.

Today we’ll take a closer look at Wegman et al’s key passage on tree-ring proxies and do a detailed side-by-side comparison with its apparent main antecedent, chapter section 10.2 in Raymond Bradley’s classic Paleoclimatology: Reconstructing Climates of the Quaternary.

That comparison leaves no doubt that Wegman et al’s explication was substantially derived from that of Bradley, although the relevant attribution appears to be missing. There are, however, several divergences of note, also in the main unattributed, and some of Wegman’s paraphrasing introduces  errors of analysis.

But the real shocker comes in two key passages in Wegman et al, which state unsubstantiated findings in flagrant contradiction with those of Bradley, apparently in order to denigrate  the value of tree-ring derived temperature reconstructions.

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Contrarian scholarship: Revisiting the Wegman report

[Update, Dec. 19: This post has been substantially revised to remove speculation about Donald Rapp’s possible role in the Wegman report. I apologize for any embarrassment caused to Donald Rapp or Edward Wegman by that speculation.

The post has also been updated to reflect new information about the provenance of Wegman et al’s section on tree ring proxies, as well as more background detail on some of the events leading up to the Wegman report. There are also  more details about  large swathes of unattributed material found in the Wegman report and in Donald Rapp’s book Assessing Climate Change.

It is clear that the circumstances and contents of both the Wegman report and Rapp’s text book deserve closer scrutiny.

Dec. 20: Comments are now open again.]

As Climategate devolves into a rerun of old battles about the “hockey stick” graph, I thought I would revisit the roots of that benighted controversy and take a look at the chaotic events of a few years back when the politicization of science (also known as the Republican war on science) really took hold.

I was planning to write another installment of the  “In the beginning” series on Steve McIntyre.  So I decided to take a look at the infamous Wegman report that Republican congressman Joe Barton relied on to ensure that the “numbers added up” (or not, as he was sure was more likely). The 2006 report was the work of a mysterious “ad hoc” committee led by George Mason University statistics professor  Edward Wegman,  along with David Scott and Yasmin Said. With its near-veneration for putative hockey-stick destroyers Steve McIntyre and Ross McKitrick, and its scornful denunciation of Michael Mann and his “social network” of like-minded researchers, the report has been a touchstone for contrarians.

But then I started thinking about something that had always bothered me. How could a trio of statistical experts, all on their own,  hope to write a  report on a field, climate science, of which they had no previous knowledge or experience?

Part of the answer lies in the close examination of  the Wegman report. Surprsingly, extensive passages from Wegman et al on proxies have turned up in a skeptic text book by contrarian author Donald Rapp.  And at least one of these common passages on tree ring proxies closely follows a classic text by noted paleoclimatologist Raymond Bradley, but with a key alteration not found in the original. Moreover, Wegman’s section on social networks appears to contain some unattributed material from Wikipedia and from a classic sociology text.

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