Category Archives: Wahl and Ammann

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 […]

Supplementary Information and Flaccid Peer Reviewing

Based on my limited experience, it seems to me that journal peer reviewing faces an interesting challenge with the increased use of Supplementary Information (and I absolutely endorse detailed SI and obviously encourage even more detailed SI). In a very non-random of articles that I know inside-out (Team journal publications), my conclusion is that, in […]

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 […]

The IPCC 4AR Zoning Variance: a CA Contest

A comment by Judith Curry reminded of a suggestion that Ross McKitrick sent me for a CA contest. Judith said: There is no fear of H/W making it into IPCC4, the closing for papers to be accepted was over a year ago. What Judith said here is what IPCC rules said prior to IPCC AR4. […]

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 […]

Juckes cites Wahl and Ammann

One of the really annoying things about Wahl and Ammann was their failure to cite our prior analysis of various MBH permutations and, then, having failed to cite these prior analyses, reproaching us for supposedly “omitting” these analyses. For example, in MM05 (EE) we discussed the relative impact of using 2 or 5 covariance PC2 […]

Juckes and the Pea under the Thimble (#1)

Juckes has much to say about several MM articles, none of it favorable and little of it accurate. Juckes, like the rest of the Team, seldom quotes our articles – instead, he typically paraphrases what we said, often creating a straw man, which he prefers to deal with. It’s a wearisome task disentangling the many […]

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 […]

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