Category Archives: Replication

The Hockey Stick and the Milankovitch Theory

The 20th century warming counters a millennial-scale cooling trend which is consistent with long-term astronomical forcing. MBH99 According to the UMass researchers, the 1,000-year reconstruction reveals that temperatures dropped an average of 0.02 degrees Celsius per century prior to the 20th century. This trend is consistent with the “astronomical theory” of climate change, which considers […]

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 […]

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 […]

Code: The Hockey Stick

%%%% Matlab version of Hockey Stick % %Mann, M. E., R. S. Bradley, and M. K. Hughes (1998), Global-scale %temperature patterns and climate forcing over the past six centuries, %Nature, 392, 779– 787. % %Mann, M. E., R. S. Bradley, and M. K. Hughes (1999), Northern %Hemisphere temperatures during the past millennium: Inferences, uncertainties, %and […]

An Example of MBH "Robustness"

In the MBH source code, they apply steps that purport to weight the temperature PCs in their regression calculations proportional to their eigenvalues. Comments on their code say: c set specified weights on data … c weights on PCs are proportional to their singular values This is one of two weighting procedures in MBH for […]

Squared Weights in MBH98

A couple of weeks ago, I said that I would document (at least for Jean S and UC) an observation about the use of squared weights in MBH98. I realize that most readers won’t be fascinated with this particular exposition, but indulge us a little since this sort of entry is actually a very useful […]

Mann's co2detrend.f Calculation

If someone felt that it was necessary to detrend the bristlecone pine-based PC1 of Mann’s AD1000 network for CO2 fertilization, it’s doubtful that the initial instinct would be to coerce the data to a network of northern Canadian-Alaskan tree ring chronologies where the possibility of regional differences must surely be allowed for. Inspection of Mann’s […]

A Little Secret

Don’t you think that someone on the Team might have been a little curious as to what bristlecone ring widths have done during the past 25 years? For this, we have the classic excuse of Michael Mann and the Team for not updating bristlecone and proxy records is that it’s not practical within the limited […]

WSJ: House Energy report on the "mutual admiration society"

John A: In today’s Wall Street Journal comes a mention of a report by three independent statisticians on the Hockey Stick It is routine these days to read in newspapers or hear — almost anywhere the subject of climate change comes up — that the 1990s were the "warmest decade in a millennium" and that […]

Bürger and Cubasch Discussion

I hope that you are following the lively discussion about Burger and Cubasch at Climates of the Past here , where Mann aka Anonymous Referee #2 is carrying on in a quite extraodinary way. I’ll probably try to weigh in over there at some point. The dialogue has exploded fairly quickly and I’ve collated some […]


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