Reply to comment by von Storch and Zorita on ‘‘Hockey sticks, principal components, and spurious significance’’

نویسندگان

  • Stephen McIntyre
  • Ross McKitrick
چکیده

[1] Von Storch and Zorita [2005] (hereinafter referred to as VZ) concur that the Mann et al. [1998] (hereinafter referred to as MBH98) principal component (PC) method ‘‘very often shows a hockey stick shaped pattern even if the data was by construction free of such structures’’ the Artificial Hockey Stick (AHS) effect. We did not claim that the AHS effect applied to all situations. We did claim that it affected MBH98 [McIntyre and McKitrick, 2005a, 2005b] (hereinafter referred to as MM05a and MM05b, respectively), where the AHS effect interacted with flawed bristlecone proxies. [2] VZ provided a simulated example where the AHS effect does not ‘‘matter’’. Unfortunately, VZ pseudoproxies dramatically overestimate the correlations of MBH98 proxies to gridcell temperature. This results in both the construction of a much stronger ‘‘temperature signal’’ in VZ simulations than is justified for MBH98 15th century proxies and the exclusion of proxies with strong nonclimatic trends, like bristlecones, which was a focus of our articles, making their example irrelevant. We discuss what is necessary to create a relevant simulation.

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Hockey sticks, principal components, and spurious significance

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تاریخ انتشار 2005