My surmise that the cross-validation R2 will be about ~0 is based on bristlecone imprinting. The no-PC method is just a variation of a bristlecone-dominated reconstruction. This is the basis of my estimate: a bristlecone-dominated reconstruction (using PCs) has a cross-validation R2 of ~0 and so (almost certainly) will a bristlecone-dominated reconstruction developed another way.

It wouldn’t do any harm to do an emulation of his no-PC method to show this and I’ll try to get to doing it. But before you blame me too much for not doing this, why don’t you blame Mann et al. for withholding this information? Also why don’t you ask Mann or Ammann at realclimate what his cross-validation R2 is for the no-PC result? I doubt that you’ll get an answer.

Please note that the “no-PC” reconstruction abandons any pretence of geographical balance and is overwhelmingly just an index of Southwestern U.S. tree growth (especially bristlecones). This is not to say that PCs are mandated as a way of avoiding this geographical imbalance, only that the geographical imbalance needs to be recognized and dealt with in some way.

That’s all in the papers which were published which can be linked-to in the sidebar under “Articles”. Also, when W&A published their supposedly “independent” version of MBH98 which included actual code which Steve could implement, it also had about 0 for the R statistic, which is probably why W&A didn’t put it in their paper either. If you’ll look around at the articles here (look especially under Categories / MBH98 / and under replication and wahl and ammann you’ll find plenty of discussion of what you’re asking.

Many thanks.

Pussy.

The scare mongers on the ‘left’ are so devoid of rational thought it would boggle one’s mind, if it were neither so tragic nor expected. Sigh.

Excellent work and an excellent expose on the political correctness of Nature and by extension, other ‘peer reviewed’ journals. If they are not willing to publish your paper BECAUSE it is accurate, reproducible, and most damning of all; in opposition to what all ‘right thinking’ people are supposed to believe, that is thier problem. In addition, I found their repeated ‘explanations’ and rejections both spurious and disingenuous. It would have been far more honest of them to simply refuse it because they did not understand the point, or (more accurately) because they did and were afraid of the political backlash that your demolition of the Mann model may have engendered.

All of which goes to point out the extreme scientific illiteracy of the current climate change debate. Warming, cooling, or stable, no one can say for certain, and until we KNOW what is going on, punishing some indulstrialized nations (primarily the US) while exempting other heavilly industrialized (and industrializing) nations (e.g. People’s Republic of China) is not the way to ‘fix’ anything. Except the egos of those who are advocating it, of course. And the attorneys.

Most respectfully.

I would say that it is extremely misleading to display the historical temperatures as temperature anomalies using a highly exaggerated vertical scale – my initial impression was that it represented temperature, but on studying the axis labelling you find that it isn’t – but must lay people would not understand this subtley, and would assume that it represents the historical temperatures.

Hence my earlier comment about the lack of any published graphs showing the mean global temperature trend over time.

There are lies, damned lies and statistics.

Mann et al. have responded to our criticism by claiming that the errors which we have identified “don’t matter” because they can “get” MBH-type results under several different methods, one of which is through not using any PCs.

Two points:
If Mann and Co. can get Hockey Stick type results without bad programming and worse statistical control, then they should withdraw MBH98 and produce the goods. It’s no use saying “our methods and statistical quality where trash before but we can replicate our results with proper methods and statistically sound data”. Replicating the Hockey Stick (or at least saying that you can) does not validate the poor science that went into MBH98 or 99.

Bet they can’t though.

I think the real skill with Mann and Co., was selling this shockingly bad piece of statistical manipulation and poor statistical control as the new paradigm of climate reconstruction. That the IPCC (or at least the three of four people who control it) believed this reconstruction at face value, and then communicating this to the world as the key evidence of 20th Century warming being anomalous.

I think its fair to say that this study is key to the claim of “greenhouse warming”, a key shibboleth of the global warming industry. As such it cannot be abandoned, for without this study, it is impossible to keep the public alarmed, and the money flowing to the vested interests of eco-alarmism.

One of the more interesting facts of the various historical records published in graph form seems to be the policy of displaying past temperatures as temperature anomalies. The various graphs you have here all show anomaly values within 1 degree Celsius of range. Why does no one publish the actual mean temperature per year over time for the last 10,000 years? This would seem a useful thing to show, or if that was done, there might be a problem?

And a temperature range within 1 degree Celsius would be physically imperceptible too yet all the debate is about variation within this miniscule range – talk about making mountains out of molehills!