Didn’t you know that after Gore’s film, another prominent actor in the GW filmography entered the scene : Michael Mann now has his own plot of a warm place : want a review ? Look here

http://filmforce.ign.com/articles/589/589674p1.html ]]>

(but don’t count on anything like: “he admitted that his models have no statistical value and that he is publishing an article shortly recanting all of his earlier claims regarding global warming / climate change)

]]>Re #29: Ed, I’ve missed this one. Where did Mann published r^2 for the *temperature* (in the 1820-step)? (Of course we can actually calculate that from the available data).

Notice also that the above formulation for gives the possibility to check the MBH98 "uncertainty limits" as Steve explained earlier. With simple manipulation, you get

Now is simply the sample variance, which can be calculated from the available data, and $R^2$s were reported, so we can calculate the left hand side which is usually known in regression as the standard error. These values match almost perfectly to uncertainty sigmas in MBH98. Since "uncertainty limits" in MBH98 are given as , we can say that those are simply twice the standard error.

The weird thing is that the standard error is calculated in the *caliberation* period. This means that making a temperature reconstruction that matches almost perfectly to the CRU record in the caliberation period (this can be done pretty well since there are relatively many proxies with respect to the length of the caliberation period), would give a reconstruction that in Mann’s opinion has almost zero "uncertainty" also in the past! Or to put in even harder way, you can generate 79 (the length of the caliberation period) or more white noise "proxies" and find a projection that matches perfectly in the caliberation period to the CRU record, so then you have a "temperature reconstruction" that has zero "uncertainty" in the past! This reconstruction would also have perfect values in the caliberation period () (of course it would be "stupid and foolish" to report the values in the verification period). The best part of this reconstruction is, however, that you can extend it back in time (or to the future!) as far as you wish!

Or you could ask about the r^2 issue, remember (thanks Danny boy) that Mann **did** publish some r^2 results in MBH98, those for the 1820 step, ask why he denied calculating r^2 when he published same, and what were the r^2 results for the 15th Century step.

On the same lines, Wahl & Amman did calculate r^2 for the 15th century, say: W&A’s emulation of MBH98 produces the same results and has been supported as doing so, and they have published r^2 statistics for the 15th century showing that the result has no merit, does he therefore agree that the same holds for MBH98, or does he repudiate W&A.

Pity it is just a bit too far for me to attend, though I guess I would feel a bit out of place.

]]>His answer will be something like, “Well, my critics keep harping on this only because they don’t understand the statistical methodologies used by the recognized experts in the field. We evaluated significance using the RE – Reduction of Error – statistic, which is the measure used by all competent climatologists for these kinds of analyses. The r2 statistic is quite simply inappropriate because it fails to accurately evaluate low-frequency skill in settings where the mean is nonstationary, which is the case in long-term paleoclimatological studies. No matter how many times I and others have explained these things, there is a small but noisy band of mostly industry-funded skeptics, who aren’t even climate scientists, who don’t understand the science and keep trying to drag the debate back a decade to re-hash old issues, like r2 versus RE, which no one in the field is paying attention to anymore, since they’ve long been settled in the peer-reviewed literature.”

To which you can reply: “So in other words the answer’s No, the r2 values weren’t significant.”

]]>Playing devil’s advocate, he could just say:

1) I didn’t say that

2) I wasn’t referring to MBH98

3) MBH98 is old hat, we admitted our errors, we’ve moved on