cc: t.osborn@uea.ac.uk, p.jones@uea.ac.uk, mann@virginia.edu, Scott Rutherford date: Mon, 03 Nov 2003 12:16:00 -0500 from: "Michael E. Mann" subject: Re: follow up as per Mike's comments earlier? to: Keith Briffa , rbradley@geo.umass.edu, mhughes@ltrr.arizona.edu HI Keith, Thanks for your message. I this as two related issues. 1) Building a bit on the initial response we've already submitted, I believe we can show beyond a reasonable doubt that the reconstruction MM produced natural results from the elimination of key predictors from our network--and that the resulting reconstructions, unlike those we published, do not pass cross-validation. We're talking to Nature right now about allowing us a formal response, and I believe this may go forward...This alone will demonstrate the invalidity of the MM03 paper, and I'd like to think that it will put the matter behind us as far as legitimate scientists are concerned--the feedback I'm already getting indicates that our colleagues believe that we have shown already strongly put in doubt the M&M result just with the limited analysis we've performed... 2) What you suggest, however, would be immensely useful. It is a natural followup to the paper that we all currently have in review in Journal of Climate w/ Scott as first author, and I see that as the first step, which is a first stab at the intercomparison issue, though it doesn't deconstruct the MBH98 predictor network. So I'd like to suggest we proceed, as you suggest, in that spirit. We can begin to coordinate plans, and it would seem natural to include Scott in this as he has really been carrying the actual work forward for us... 3) In parallel, we have been working on a considerable expansion of the original MBH98 network for further reconstructions, and perhaps we should discuss how this might best mesh w/ your efforts. Further comments? Thanks, mike At 04:51 PM 11/3/2003 +0000, Keith Briffa wrote: Mike , Ray, Malcolm We three have been discussing the weeks shenanigans and thought we should start the wider discussion on the concept and practical aspects of someone (perhaps us - perhaps not us) doing the "independent" audit of your 98 and/or 99 work. It is clear that the debate as regards the M and M results will now likely stall , until one or more people undertake this - but it is unlikely to go away until such time as something is done. The problem , however, is what this audit would set out to do. If it constitutes taking the exact same data and exact implementation of your method - there seems little value in doing it - the result will be identical to your result(s). The question then , revolves around a fuller experiment in the use of various selection criteria for retaining subsets of the predictors , and presumably working towards gaining some better impression of the stability of the results , and the sensitivity to the inclusion of particular predictors. We could perhaps also compare results with those achieved using other methods (such as our Orthogonal Spatial Regression)? We would not be attempting to do any new reconstructions. The question then , stimulated again by Mike's message , and the message from the Editor of E and E, is whether we should consider going ahead here, with some such work? We are already motivated to look at the role of the tree-ring data (in collaboration with Malcolm and Ed hopefully, looking at stuff like standardisation issues, the western U.S. recent trend correction etc.) , but we feel some discussion among all of us would help to clarify opinions and prospects for a wider look at the robustness of the Mann98/99 result. We have no particular axe to grind , but it is almost certain that there will be some pressure for some such work, and we suspect that DEFRA here will be quizzed by various bodies for their opinion on this. If so, why not us rather than others ? It may be that anything we do here would not be seen as "independent" by the skeptics anyway ( and we would not consider doing it without some appropriate level of interaction with you lot) - but in the end , what counts, is what is published in the peer-review literature.It was important to get your statement out , but it needs to be followed up now by one or more studies by other groups. We could go with the candidate predictor set you used and do a Monte Carlo approach to selection over different periods , or add in other predictors or ....what? What do you think? We might need to go for a very small amount of money from DEFRA ( to pay Harry or someone just to manipulate palaeo data , and then after implementing the method(s) and deciding on the scheme, run the numerous experiments and synthesize results), or we may be able to do it by diverting his time from some other stuff anyway. To get the discussion going , we wish to ask your opinion(s) on the concept, level of interaction between us and you guys ( in planning , or also implementation , and synthesis, writing up?). What about this issue of our perceived independence - do we give a damn? Keith, Tim, Phil -- Professor Keith Briffa, Climatic Research Unit University of East Anglia Norwich, NR4 7TJ, U.K. Phone: +44-1603-593909 Fax: +44-1603-507784 [1]http://www.cru.uea.ac.uk/cru/people/briffa/ ______________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [2]http://www.evsc.virginia.edu/faculty/people/mann.shtml