date: Thu, 26 May 2005 09:03:16 -0400
from: "Michael E. Mann" <mann@virginia.edu>
subject: Fwd: RE: NATURE: 2005-02-02202
to: Phil Jones <p.jones@uea.ac.uk>, tim Osborn <t.osborn@uea.ac.uk>, Keith Briffa <k.briffa@uea.ac.uk>, Scott Rutherford <srutherford@rwu.edu>, "Wahl, Eugene R" <wahle@alfred.edu>, Caspar Ammann <ammann@ucar.edu>, mann@virginia.edu

   Dear All,
   So here is where we stand w/ the comment. Nature seemed adamant about not allowing us to
   focus on the synthetic example (ridiculous in my opinion), so I've been forced instead to
   move this into the Mann et al  (pseudoproxy) J. Climate paper. That  was in the final stage
   of revision, but Andrew Weaver has allowed me to add the Moberg-simulation results into the
   final version since it specifically addresses a request of one of the reviewers of our
   paper (who wanted to see us discuss implications of the pseudoproxy analyses for the Moberg
   et al example). I'll send everyone a copy of that when its finalized.
   They will (see below) allow us to provide some discussion of the synthetic example,
   referring to the J. Cimate paper (which should be finally accepted upon submission of the
   revised final draft), so that should help the cause a bit.
   I'm going to try to produce a revised draft of the Nature comment that confirms to what was
   outlined by Heike, and then send it to all of you for comments. At that point, we can
   decide if this is worth submitting, or if it is too flimsy w/out a supporting synthetic
   example. It would be extremely helpful if Tim or someone else could provide a very simple
   example (short of model-based pseudoproxies, etc.) that demonstrates the potential for bias
   we are talking about?
   I hope to be in touch again soon w/ a revised draft. Meanwhile, feel free to provide me any
   feedback...
   thanks,
   mike

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     From: "Langenberg, Heike" <H.Langenberg@nature.com>
     To: "'Michael E. Mann'" <mann@virginia.edu>
     Subject: RE: NATURE: 2005-02-02202
     Date: Thu, 26 May 2005 10:49:34 +0100
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     Dear Mike,

     thank you for the note. That scenario sounds fine, but please keep the discussion of the
     synthetic example brief (50-100 words). We will ask the referees whether they think the
     discussion of the results in the Journal of Climate adds important content to the
     comment, and if they feel it does, there is no objection from our part.

     I hope this will clarify our position for you.

     Best wishes,
     Heike

          -----Original Message-----
          From: Michael E. Mann [[1]mailto:mann@virginia.edu]
          Sent: 26 May 2005 00:01
          To: h.langenberg@nature.com
          Subject: Re: NATURE: 2005-02-02202
          Dear Heike,
          I'm sorry I've been unable to get back to you sooner.
          We have chosen to include our synthetic example in the final revisions of our
          manuscript to be published in "Journal of Climate", and it appears that the
          manuscript has reached the stage of final acceptance. So this part of our original
          submitted comment will now appear elsewhere (J. Climate) and obviously it would be
          inappropriate for us to publish those results again in Nature. Therefore, including
          this in our comment is a moot issue now.
          So, if we chose to revise our original submitted comment along the lines you have
          suggested in your email below, focusing on the application to the Mann and Jones
          (2003) dataset & demonstration that the procedure inherently inflates the
          low-frequency variability (and eliminating the latter part of the comment which
          focuses on the synthetic example), would there be any objection on Nature's part to
          us briefly discussing the synthetic network results in the context of the comment,
          referring to our manuscript accepted in Journal of Climate for further details?
          We're very much hoping that this is a scenario with which Nature would be
          comfortable. I
          thanks in advance for your response,
          Mike
          At 11:47 AM 5/10/2005, h.langenberg@nature.com wrote:

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          Dear Mike,
          thank you for the note, asking for clarification of our decision. However, I am
          afraid I am unable to follow your argument and therefore suggest that you revise
          your contribution along the lines indicated in our previous letter, if you wish to
          pursue publication in Nature.
          Specifically, both referees feel that a quantification of the possible bias in the
          Moberg et al estimate of low-frequency variability based on your synthetic example
          (the second part of your manuscript) is flawed or at least highly uncertain given
          the assumptions that go into your reconstruction (as, for example, outlined in
          referee 1's point 1). Based on these criticisms, we decided to decline publication
          of the present version of the comment, and I am sorry to say that we are unable to
          conclude that your remarks below address these criticisms satisfactorily.
          However, referee 2 notes that you identify a weakness in the Moberg et al approach
          (that is, that they normalise the data before filtering).
          We offered the possibility to resubmit specifically because we feel that this point
          (if significant) may be of interest to our broader audience. It seems to us that the
          referee's suggestion of providing a direct comparison between the Moberg
          reconstruction and results obtained with the same method but after correction of
          this weakness would be the most convincing quantification of its effect.
          I hope these comments will help to clarify our decision and help you decide how best
          to proceed.
          Best wishes,
          Heike
          -----Original Message-----
          From: Michael E. Mann [[2]mailto:mann@virginia.edu]
          Sent: 06 May 2005 19:58
          To: h.langenberg@nature.com
          Subject: Re: Decision on Nature Manuscript 2005-02-02202
          Dear Heike,
          Thanks for your email. We would be happy to revise our contribution for
          consideration by Nature.
          However, let me first seek some further clarification from you. Your email indicates
          that our revised comment should quantify "the spurious contribution to long-term
          variability introduced in the Moberg et al. reconstruction due to the erroneous
          normalising procedure prior to the filtering process". This is indeed what we felt
          we were doing, but apparently this was not communicated as clearly as it needed to
          be.
          In particular, your email suggests that our revised version  eliminate the latter
          half of the contribution (the synthetic proxy or "pseudoproxy" analysis). This is
          problematic, because this is actually where the key scientific points are made, and
          where general conclusions about the potential bias of the method can be drawn.
          The first half of our contribution simply shows that using the Moberg et data data
          applied to the Mann and Jones (2003) reconstruction inflates the low-frequency
          variance. It does not (nor can it) address whether or not the inflation of variance
          is realistic or not. The reviewers are in fact incorrect when they conclude that
          this part of our analysis demonstrates a bias in the Moberg et al method. It
          doesn't!
          Only an analysis (as described in the second half of our comment) in which the exact
          answer is known, so that competing methods can be objectively tested against a
          "ground truth", can address whether the additional variance is spurious or not. In
          other words, with a synthetic example, where, unlike the real world, the actual
          climate history  is known, we can determine whether or not a particular method
          returns the correct reconstruction. This was described in some detail in the
          supporting manuscript we provided, which was presumably seen by the reviewers? But
          the reviewers, at least in part, fail to have grasped this key point.
          In the synthetic example, we showed that the Moberg et al method does not return the
          actual model history when applied to realistic synthetic proxies. So there can be no
          question  that the method exhibits a bias. Its purely a matter of how *large* the
          bias is.  We feel that this point has somehow been lost on the reviewers. The degree
          of bias does indeed depend on signal-to-noise ratios, and we can easily quantify
          that in a revised comment.  Part of the confusion (at least with reviewer #2)
          appears to have been with our Figure 3 which left out one important piece of
          information (the uncertainty in the Moberg et al-type reconstruction). That is
          easily rectified as well.
          So we would like to request that we not drop the synthetic proxy or "pseudoproxy"
          aspect of the analysis, which is absolutely essential to the argument we are making,
          but instead revise this part of the analysis to address the criticisms raised by the
          original authors, and to clarify precisely what is shown by such a synthetic
          example. In the process, we would we would quantify, as requested, the dependence of
          the bias on e.g. signal-to-noise characteristics of the pseudoproxy data.
          Please let me know if it would be acceptable for us to proceed as suggested above.
          Thanks in advance,
          Mike
          This email has been sent through the NPG Manuscript Tracking System NY-610A-NPG&MTS
          ______________________________________________________________
                              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
                   [3]http://www.evsc.virginia.edu/faculty/people/mann.shtml

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   ______________________________________________________________
                       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
            [4]http://www.evsc.virginia.edu/faculty/people/mann.shtml

