Tag Archives: ammann

Data Stonewalling Resumes

Ryan O asked serial Mann coauthor, Caspar Ammann, for supporting data for Ammann et al (PNAS 2007), which was referred to in CCSP (2009c) Past Climate Variability and Change in the Arctic and at High Latitude, an assessment report that was, in turn, cited in the EPA Endangerment Finding. Ryan’s request was as follows: the […]

Pielke Jr discusses the Bishop and the Stick

Roger Pielke Jr has written a gracious post , following up on Bishop Hill’s post and considering the issues as they pertain to science policy, and, in particular, the processes of peer review and due diligence, which have informed many of my posts. He refers to and reconsiders a post that I wrote for Prometheus […]

Bishop Hill: Caspar and the Jesus Paper

Reader Perry writes in reporting an interesting narrative of the Caspar Ammann affair at Bishop Hill’s blog here. IT is a detailed narrative written in a lively style of a story that’s been followed here for a few years and re-visited last week with the release of the Ammann SI. The article is very flattering […]

Reconciling to Wahl and Ammann

When Wahl and Ammann’s script first came out, I was able to immediately reconcile our results to theirs – see here. As Wegman later said: when using the same proxies as and the same methodology as MM, Wahl and Ammann essentially reproduce the MM curves. Thus, far from disproving the MM work, they reinforce the […]

Caspar Ammann, Texas Sharpshooter

The Texas Sharpshooter fallacy is a logical fallacy where a man shoots a barn thirty times then circles the bullet holes nearest each other after the fact calling that his target. It’s of particular concern in epidemiology. Folks, you are never going to see a better example of the Texas Sharpshooter work itself out in […]

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 […]


Get every new post delivered to your Inbox.

Join 2,901 other followers