Category Archives: Replication

MBH and Partial Least Squares

Right now, I’m working on two main projects where I intend to produce papers for journals: one is on the non-robustness of the “other” HS studies; the other is on MBH98 multivariate methods. The latter topic is somewhat “in the news” with the two BàƒÆ’à‚⻲ger articles and with the exchange at Science between VZ and […]

Detrended in Amherst

Wahl et al [2006 ] fulminated as follows : The VS04 results have been interpreted to cast serious doubt on the MBH reconstruction. … However, these results are in large part dependent on a detrending step not used by MBH, which is physically inappropriate and statistically not required. The take-away message for the climate community […]

Reconciling Zorita

Eduardo Zorita and I are in the process of reconciling some results. We have taken one issue off the table – VZ implemented Mannian PCs accurately enough that this does not account for any differences between our results and theirs. So I take back some observations and I’ll place updates in appropriate places. In fairness […]

Wahl, Ritson and Ammann on VZGT

Wahl, Ritson and Ammann, the authors of two rejected comments on MM05 to GRL – see here and here for our Replies to the rejected comments – have joined forces and pulished a critical comment on Von Storch et al [2004] in Science, to which von Storch et al have issued a Reply. realclimate has […]

Not A Solution to the Caramilk Secret

Update: the following does not explain the Caramilk secret of MBH99 confidence intervals, which remains unexplained and mysterious. End Update. OK, Mann starts with a sigma obtained from the standard errors in the calibration period from his hugely overfitted model. He uses this in MBH98. In MBH99, recognizing the autocorrelation in the residuals, he adjusts […]

More on MBH Confidence Intervals

I’ve posted in the past on the mystery of MBH confidence interval calculations, especially the mysterious MBH99 confidence intervals (another Caramilk secret). In our NAS panel presentation and perhaps before, I’d speculated that MBH98 confidence intervals, rotundly described in MBH98 as “self-consistently estimated” were nothing other than twice the standard error of the (overfitted) calibration […]


It often feels like shoveling out a swamp in dealing with the misrepresentations of our stuff. Someone over at Tim Lambert has said that I “originated incorrect information” about Mann’s CENSORED directory: So my original point stands that McIntyre originated incorrect information such as the idea that the data in the directory only has […]

Why peer reviewed publication is not enough

Obviously Climate Audit has captured a small part of the zeitgeist of the scientific world, especially in regards to the obvious failures of peer review to detect bad practice and scientific misconduct. It has been asked by some climate scientists why access to original data and full disclosure is so important, as if proper audit […]

More Linear Algebra

I’m not sure that there’s a huge demand for more linear algebra on MBH98, but here’s the rest of the proof that the NH temperature index in an MBH98-type calculation is simply a linear combination of proxies and, when only one temperature PC is reconstructed, the weights are proportional to the correlation between each proxy […]

MBH Calibration-Estimation Procedure

What I’m going to show here is that the MBH98 method can be reduced to a few lines of code and, in doing so, show some other interesting results as well. Today I’m just going to get to the reconstructed temperature PCs, but I’ll show that these are linear in the proxies and later show […]