Tag Archives: Mann et al 2008

M08 with realdata

Yesterday we noted that “validation” in M08 means that the average of the “late-miss” and “early-miss” RE statistic is above a benchmark of about 0.35. I take no position at present whether this unusual methodology means anything, though I’m a bit dubious. I also observed that the with-dendro reconstructions added surprisingly few series in the […]

Mann and his bristlecones

Gavin Schmidt and others have claimed that the M08 usage of the Tiljander sediments didn’t ‘matter’, because they could “get’ a series that looked somewhat similar without the sediments. They’ve usually talked around the impact of the Tiljander series on the no-dendro reconstruction. But there are two pieces of information on this. A figure added […]

The No-Dendro Illusion

In September 2008, Mann et al reported a “significant development” in paleoclimate reconstructions – a “skillfull” reconstruction without tree ring data for over 1300 years. A skillful EIV reconstruction without tree-ring data is possible even further back, over at least the past 1,300 years, for NH combined land plus ocean temperature (see SI Text). This […]

Make a stick, make a stick

NASA blogger Gavin Schmidt as part of his ongoing attempt to rehabilitate Mannian paleoclimate reconstructions, characterized here as dendro-phrenology, has drawn attention to a graphic posted up at Mann’s website in November 2009. In this graphic, Mann responded to criticisms that his “no-dendro” stick had been contaminated by bridge-building sediments despite warnings from the author […]

Yet another Upside Down Mann out

Science published today yet-another-Mann-et-al-reconstruction: Michael E. Mann, Zhihua Zhang, Scott Rutherford, Raymond S. Bradley, Malcolm K. Hughes, Drew Shindell, Caspar Ammann, Greg Faluvegi, and Fenbiao N: Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly, Science 326 (5957), 1256. [DOI: 10.1126/science.1177303]. Seems to me that Mann has re-discovered the Medieval […]

Upside-Side Down Mann and the “peerreviewedliterature”

In Andrew Revkin’s recent blog posting, he made the following observation about blogs, referring in particular to Climate Audit: What is novel about all of this is how the blog discussions have sidestepped the traditional process of peer review and publication, then review and publication of critiques, and counter-critiques, by which science normally does that […]

More Upside-Down Mann

Previously, we discussed the upside-down Tiljander proxies in Mann et al 2008. Ross and I pointed this out in our PNAS comment, with Mann denying in his answer that they were upside down. This reply is untrue (as Jean S and UC also confirmed.) Andy Baker’s SU967 proxy is used in Mann 2008 and is […]

More Z-Score Opportunism

We’ve frequently observed that the reduction of data to standard deviation units (z-scores) is often associated with seemingly opportunistic orientation of the data sets. Often this is buried in the multivariate methodology. Principal components and RegEM can both function to opportunistically provide orientations to “proxies”. In Mann 2008, we saw pretty examples of proxies being […]

More Stupid Pet Tricks

Yesterday I left my exposition of Mannian CPS just before trying to do a NH composite. There was another stupid pet trick left, that made replication of this step a little trickier than one would think. UC had sent me a file entitled NHmean.txt (which I’ve placed online), which was produced during gridboxcps.m, and proved […]

Mannian CPS: Stupid Pet Tricks

David Letterman sometimes has a segment entitled “Stupid Pet Tricks”, which is an apt title for today’s post – more parsing of Mannian CPS, recently discussed here. With helpful contributions from Jean S, UC and Roman M, I can now pretty much replicate Mannian CPS, but only through a variety of devices that fall into […]

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