Tag Archives: wahl

Fortress Met Office continued

More obstruction from the Met Office, in which they have changed their obstruction strategy. Previously they said that Mitchell had destroyed all of this email correspondence. This prompted David Holland to ask for information on the date of the destruction and on records management policy at the Met Office. Rather than answer the unanswerable, the […]

Fortress CRU #2: Confidential Agent Ammann

On March 31, 2008, David Holland sent a letter to Keith Briffa asking about several IPCC issues. In correspondence released from the Hadley Center, Briffa indicated his intention of being unresponsive. On May 15, Briffa sent an unresponsive reply to Holland, following which Holland initiated a FOI request on May 27, 2008 leading to an […]

Fortress CRU

As noted in other posts, IPCC policies state: All written expert, and government review comments will be made available to reviewers on request during the review process and will be retained in an open archive in a location determined by the IPCC Secretariat on completion of the Report for a period of at least five […]

The Dog That Didn't Bark

This is the title of a famous Sherlock Holmes story and not intended as a slight to any individual. Take a look at the Review Comments for AR4 Second Draft Chapter 6 online here. While I was reviewing these comments, I noticed that there are no reported comments on chapter 6 from Caspar Ammann, one […]

The RE Benchmark of 0

In MM2005a,b,c, we observed that the RE statistic had no theoretical distribution. We noted that MBH had purported to establish a benchmark by simulations using AR1 red noise series with AR1=0.2, yielding a RE benchmark of 0. We originally observed that high RE statistics could be obtained from PC operations on red noise in MM2005a […]

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 […]

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. […]


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 […]


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