Tag Archives: ammann

The MBH AD1450 Network

Most of my previous discussion of MBH pertained to the AD1400 network. In recent discussion over at Tamino, some of the posters have stated that BCPs only matter for the AD1400 network and that everything is fine for the AD1450 and later networks, relying here on statements in Wahl and Ammann 2007. (I don’t suppose […]

Where's Caspar?

As you know, we are eagerly awaiting the publication of the following article by Wahl and Ammann reported here: Wahl, E and C Ammann (In press). “Robustness of the Mann, Bradley, Hughes reconstruction of northern hemisphere surface temperatures: Examination of criticisms based on the nature and processing of proxy climate evidence.” Climatic Change (accepted). May […]

Overfitting by Inverse Regression

Wahl and Ammann 2006 reported that they could “get” something that was sort of HS-ish without principal component analysis. It wasn’t through a simple mean or CVM; it was through Mannian inverse regression. Juckes et al shows many reconstructions using “inverse regression”, mentioning in his conclusions that inverse regression caused over-concentration on a few proxies. […]

Q.e.d.

One point that Wahl and Ammann and ourselves agree on, but which Juckes appears to contest, is that principal components methodologies applied to AD1400 MBH98 networks result in upweighting or downweighting of bristlecones. Their Scenario 6 shows reconstruction results without bristlecones for covariance, correlation and Mannian PCs. I have no dispute with these calculations although […]

Wahl and Ammann Again #2

Here’s a pretty little graph that I think that you’re going to see more of. One is using the Wahl-Ammann variation of MBH methodology applied to MBH data; the others are from low-order red noise. Pink – no PC reconstruction from WA without strip-bark and Gaspé; black – from low-order red noise. I worked this […]

Wahl and Ammann Again #1

I asked KNMI what were the studies that had "refuted" our work. It seems to be Wahl and Ammann. I’ve never understood the traction of Wahl and Ammann with climate scientists. I doubt that any of them have worked through the details, but Wahl and Ammann issued a press release that all our claims were […]

Letter to Climatic Change

I was asked to review the Wahl and Amman submission in May 2005 and recently posted up my review here. The first recommendation in my review was that all Wahl and Ammann remove all arguments that depended on their rejected GRL article. They didn’t and now it’s come back and should haunt them. Despite providing […]

The RE Benchmark in A&W

There’s an interesting irony in the GRL rejection of the Ammann & Wahl Comment and it will be interesting to see how this gets handled. It turns out that the A&W Climatic Change depends on their GRL submission for their test of statistical significance for the RE statistic. So even though the GRL referee thought […]

Ammann and Wahl – July 2005 Review

I’m posting up our July 2005 review of Ammann and Wahl. The recently accepted A&W version is here. I’m posting this up for a variety of reasons. Mann relied heavily on Ammann and Wahl in his NAS panel testimony (which wasn’t even online as accepted last week) and so it’s hard to finish off the […]

Peer Reviewing Ammann and Wahl #1 – The Correspondence

Mann cited Ammann and Wahl’s recently released paper at NAS (which was not available to us in time for the NAS panel, although I’d seen and reviewed an earlier draft.) After reading it, Per said that he thought that the reviewers had done a lousy job. Now I was only a reviewer for the first […]

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