Tag Archives: preisendorfer

Richard Smith on PC Retention

Richard Smith, a prominent statistician, has recently taken an interest in multiproxy reconstructions, publishing a comment on Li, Nychka and Ammann 2010 (JASA) here and submitting another article here. I’ll try to comment more on another occasion. Today I want to express my frustration at the amount of ingenuity expended by academics on more and […]

Rule N and Weighted Regression

Today’s post, which has a forbidding title, contains an interesting mathematical and statistical point which illuminates the controversy over how many PCs to retain. In my re-visiting the totally unknown corner of Mannian methodology – regression weights and their determination – I re-parsed the source code, finding something new and unexpected in Mannian methodology and […]

A Challenge to Tamino: MBH PC Retention Rules

Today I wish to re-visit an issue discussed in one of the very first CA posts: did MBH98 actually use the PC retention rules first published in 2004 at realclimate here and described both there and by Tamino as “standard” selection rules. Much of the rhetorical umbrage in Tamino’s post is derived from our alleged […]

"Mannian" PCA Revisited #1

One of Hansen’s pit bulls, Tamino, has re-visited Mannian principal components. Tamino is a bright person, whose remarks are all too often marred by the pit bull persona that he has unfortunately chosen to adopt. His choice of topic is a curious one, as he ends up re-opening a few old scabs, none of which […]

Huybers #2: Re-Scaling

Huybers’ second and more interesting (to me) issue pertains to the benchmarking of the RE statistic.I’m going to start in the middle of this issue. If I start with the history e.g. defining the RE statistic and showing its history (and I just tried), it’s hard to get to the punch line. So what I’m […]

Roll Over, Preisendorfer

I think that Preisendorfer would roll over in his grave if he saw how Ammann, Schmidt and Mann were bastardizing his Rule N.

Source Code: Preisendorfer’s Rule N

Here’s a comment on handling of Preisendorfer’s Rule N in the code dump; I’ll post some further comments on Preisendorfer on Preisendorfer’s Rule N in a few days. There is NO source code showing the application of Preisendorfer’s Rule N to tree ring networks – a battleground issue, if you will. There is some source […]

Preisendorfer on Centering "Conventions"

In our GRL article, we pointed out that MBH98 had misrepresented their principal components methodology as being "conventional", when it wasn’t. At realclimate , they argued that it was an alternative centering "convention".

Errors Matter #3: Preisendorfer’s Rule N

In the last two days, I’ve argued that it’s insufficient for Mann et al. to merely “get” a hockey stick shape some other way, but that they have to show that any such salvage reconstruction meets the representations and warranties of MBH98 as to reasonably even spatial sampling, robustness, statistical skill and proxy validity. I’ve […]

Was Preisendorfer’s Rule N Used in MBH98 Tree Ring Networks?

Mann et al. have recently argued that they can salvage MBH98-type results, even with correct PC calculations by also using “the standard selection rule (Preisendorfer’s Rule N) used by MBH98″. They say that this method permits them to retain 5 PCs in the North American network. The reason why this matters to them is that […]


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