Anthony Watts draws attention to a new Nature article (LI et al 2011) purporting to reconstruct El Nino activity. The Supplementary Information shows a very obvious Chladni pattern, that went unnoticed by the Nature reviewers. The eigenvector shown here is what one would expect from principal components carried out on spatially autocorrelated data on a […]
Some of the CA posts that I’ve found most interesting to write have been about identifying Chladni patterns in supposedly “significant” reconstructions when principal component methods have been applied to spatially autocorrelated red noise. (This is by no means a new observation, as warnings about the risks of building “castles in the air” using principal […]
Yesterday, I showed an interesting comparison between the 3 Steig eigenvectors and “Chladni patterns” generated by performing principal components on a grid of spatially autocorrelated sites on a disk. Today I’ll show a similar analysis, but this time using a random sample of points from actual Antarctica. The results are pretty interesting, to say the […]
Last year, I did a few posts connecting spatial autocorrelation to something as mundane as the Stahle/SWM tree ring network. In the process, I observed something that I found quite interesting – that principal components applied to geometric shapes with spatially autocorrelated series generated Chladni patterns, familiar from violins and sounds. The Antarctica vortex represents […]
Although climate scientists keep telling that defects in their “hockey stick” proxy reconstructions don’t matter – that it doesn’t matter whether they use data upside down, that it doesn’t matter if they cherry pick individual series depending on whether they go up in the 20th century, that it doesn’t matter if they discard series that […]
A common opinion (e,g, Scott Adams) is that the “other proxies”, not just Mann’s stripbark bristlecone tree rings, establish Hockey Stick. In today’s post, I’ll look at PAGES2K Antarctic data – a very important example since Antarctic isotope data (Vostok) is used in the classic diagram used by Al Gore (and many others) to illustrate […]
As CA readers are aware, Stephan Lewandowsky of the University of Western Australia recently published an article relying on fraudulent responses at stridently anti-skeptic blogs to yield fake results. In addition, it turns out that Lewandowsky misrepresented explained variances from principal components as explained variances from factor analysis, a very minor peccadillo in comparison. In […]
Do some of you remember Steig et al 2009, a pre-Climategate Nature cover story? Like so many Team efforts, it applied a little-known statistical method, the properties of which were poorly known, to supposedly derive an important empirical result. In the case of Steig et al 2009, the key empirical claim was that strong Antarctic […]
Geoff Sherrington and others on the First Difference Method post have requested a post for discussing Kriging. I am new to Kriging myself, so please correct me if I make any errors here. Steve McIntyre (who may be on the beach at the moment!) is far more knowledgeable, and has posted about the topic frequently […]
In his RC post yesterday – also see here – Steig used North et al (1982) as supposed authority for retaining three PCs, a reference unfortunately omitted from the original article. Steig also linked to an earlier RC post on principal components retention, which advocated a completely different “standard approach” to determining which PCs to […]
Climate Audit 