The NAS Panel notes the following about several statistics used in proxy studies: If are the predictions from a linear regression of on the proxies, and the period of interest is the calibration period, then RE, CE, and are all equal. Here’s a result about MBH methods (and applicable to related methods with re-scaling) that […]
There is another terrific article by Bürger and Cubasch posted up here . I’ve just looked at for a few minutes so far and it will take time to fully digest, but one can tell right away that it is a very interesting and stimulating article. Gerd Bürger notified me of it and I therefore […]
(John A): On Jerry Pournelle’s fascinating weblog, a poster has mentioned Steve McIntyre’s expanded horizons into the world of multiproxy studies and the revealing reply to the NAS Panel by D’Arrigo in praise of cherrypicking proxies because "that’s what you have to do if you want to make cherry pie". Jerry responds: The basis assumption […]
The NAS Panel claimed that MBH98 was the "first systematic" multiproxy study. It wasn’t; it didn’t even claim to be, citing Bradley and Jones 1993 and several other studies of the same vintage as predecessors. Crowley was a peer reviewer for the NAS panel, who presumably relied on him to catch this sort of mis-step. […]
Jean S pointed out the following quote from the NAS Report and suggested that this be discussed: The first systematic, statistically based synthesis of multiple climate proxies was carried out in 1998 by M.E.Mann, R.S.Bradley and M.K. Hughes (Mann et al. 1998); their study focused on temperature for the last 600 years in the Northern […]
Interesting title, no? What if I added Principal Components to this odd concatenation of concepts? Galluccio et al 1998 published a paper with the above title here, which has led to a number of follow-ups, which you can locate by googling. I’ll try to summarize Galluccio’s basic idea and then tie it back into principal […]
One bit of housekeeping that I want to tidy up before more NAS postings: a couple of months ago, Eduardo Zorita kindly sent me comprehensive data from ECHO-G, on which, unfortunately, I’ve so far not been able to spend as much time on so far as I would have liked. So much to do, so […]
Readers of this site are familiar with our concern over the use of bristlecones/foxtails in MBH98-99 and other multiproxy studies. The NAS Panel found in one place that "strip-bark samples" (which Graybill sought out in his bristlecone collections) should "not be used". They also reported that the MBH results were "strongly dependent" on "Great Basin […]
When you go through the NAS Panel report closely, it’s amazing how many of our views were adopted – on principal components, statistical skill, statistical methods, bristlecones. I started out trying to make a post showing our views side-by-side with those of of our opponents and those of the NAS Panel, but the post quickly […]
In the NAS press conference, Bloomfield said that you could get a Hockey Stick from an average of the proxies. This was a pretty misleading comment. You CAN’T get a HS from averaging the MBH98 proxies. We showed this to the NAS panel on our presentation as follows: The simple mean of the Mann et […]
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