What data is climate scientist Michael Mann still withholding?

The "r-squared correlation coefficient" is something you would have learned about in ANY class where you had to analyze goodness-of-fit, whether it was a laboratory class in physics, a statistics class, or even an engineering class.

EDIT: Sorry, the way you phrased your question it sounded like you were unfamiliar with it. Could you give a reference to where it says he is "withholding" this information? Since other studies have essentially confirmed Mann's results, did they withhold their correlation coefficients also?

Another EDIT: This may be what you're referring to, Mann says

"My colleagues and I did not rely on this statistic in our assessments of “skill” (i.e., the reliability of a statistical model, based on the ability of a statistical model to match data not used in constructing the model) because, in our view, and in the view of other reputable scientists in the field, it is not an

adequate measure of “skill.”

Instead, they used a different statistical quantity, the reduction of error or RE statistic, which is generally accepted to be superior for reconstructions. He then goes on to point out

"...the results of the McIntyre and McKitrick analyses fail verification tests using the accepted metric RE. This is a key finding of the Wahl and Ammann study cited above. This means that the

reconstructions McIntyre and McKitrick produced are statistically inferior to the simplest

possible statistical reconstruction: one that simply assigns the mean over the calibration

period to all previous reconstructed values. It is for these reasons that Wahl and

Ammann have concluded that McIntyre and McKitrick’s results are “without statistical

and climatological merit."

http://www.realclimate.org/Mann_response_to_Barton...

So there's your answer, he's not going to hand over something that he didn't use.

EDIT: Sorry jim z, I was trying to answer Ottawa Mike's question about Michael Mann by going to Michael Mann himself for his reasoning (correct or incorrect), when I obviously should have been going to the non-scientist pretend-Lord Monckton, which was your source. It must have been an oversight, but in climate science school they never taught us that minor British royalty were the ones to consult on matters of science.

My guess is that following an envelope of white powder showing up in his office, Mann's willingness to accommodate requests regarding his research hover right above the level of what he is legally forced to do.

@ Jim Z - R^2 does not in any way give a measure of model predictive accuracy (as per your quote). R^2 doesn't even tell you if you have the right model, it simply states how well the observed data fit a generalized trend (linear or not).

@ Sagebrush - neither Mann nor his hockey stick graph make projections. You're getting your slanders mixed up, go do some homework or continue forward willfully ignorant (this is really a hypothetical choice, I know which way you're going)

@Mike L - odd statement considering your previous support of recent reconstructions from tree rings that support your political opinion. Odd, indeed...

@Sagebrush, lol, sick burn bro...

It doesn't matter unless you are a dupe of WattsUp.

“buried deep within the paper, Amman and Wahl had quietly revealed their verification r2 figures, which were, just as McIntyre had predicted, close to zero for most of the reconstruction, strongly suggesting that the hockey stick had little predictive power.”

In fact, Mann's statisitcal methods were shoddy and primitive and I think they were downright dishonest. Pegminer pretends to know otherwise. Rusty is right and Peg claims to be a climate scientist? It appears to me that Peg isn't really interested in facts and is just regurgitating AGW talking points.

The Hockey Stick Illusion by Montford provides a very good account of what happened with all this. It has been awhile since I read it but alarmists would probably have their heads spin around and start spewing pea soup if they read it. Apparently, they can only read leftwing blogs.

YA should really deal with these multi-account juveniles. When they can't win arguments, they resort to smears or suppression. Nothing new about that.

I would like to know how He divines temperatures out of tree rings .

(Tree rings can only tell dry years thin , wet years thick you can not find temperatures

on them . Mann is lying that he can .)

Well he can't. Because his projections haven't come true. You can bet your bottom dollar that if they would have come true he would be tooting his horn.

David b: We all know what he meant to accomplish with his hockey stick. If you don't then - - -maybe you should go back to school. All the way back to grade school.