The National Post has a big feature on Hugo Chavez, President of Venezuela, who’s much in the news as a result of a fatwa on him by Pat Robertson. This post has nothing to do with climate. I happened to be in Caracas during the Chavez coup attempt in 1992 and this is just a personal reminiscence. Continue reading →
The Boston Globe has an interesting puff piece on Ray Bradley. Continue reading →
Granger and Newbold [1974] provided examples of spurious significance in a random walk context. This has been extended by various authors to a number of other persistent processes. Granger and Newbold suggested that the DW statistic could be used to test the autocorrelation in the residuals, giving a test that could be used in a relatively unsupervised way to check for spurious relationships. Here are some examples from cases familiar to readers: Gaspé cedars, the MBH98 NOAMER PC1, the MBH98 reconstruction and satellite temperature trends. Continue reading →
I think that there is too much preoccupation in the analysis of NH urban gridcells. As an exercise, I plotted the ACFs and gridcells for a transect at 7.5S from 177.5W to 177.5E. The presentation here is not very pretty but I think that the graphs are interesting taken as a whole. I draw no conclusions, other than it’s quite puzzling to see the difference between the patterns in adjacent gridcells and one would like to see some detailed analysis justifying the details. Continue reading →
Nature has published a ground-breaking new study of peer review. Continue reading →
I have previously discussed here and here Mann’s answer to the following question from the House Committee:
"7 c. Did you calculate the R2 statistic for the temperature reconstruction, particularly for the 15th Century proxy record calculations and what were the results?"
Mann stated:
"My colleagues and I did not rely on this statistic in our assessments of “skill” (i.e., the reliability of a statistical model, based on the ability of a statistical model to match data not used in constructing the model) because, in our view, and in the view of other reputable scientists in the field, it is not an adequate measure of “skill.”
My previous discussion was based on the Supplementary Information where the cross-validation R2 statistic is notably not reported. However, I did not discuss the following Figure from the Nature article itself, which is well worth discussing. 
Continue reading →
Ian Castles, the well-known economist, has sent in the following post as a comment on another topic, which I have taken the liberty of posting up here. Ian writes:
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"Spurious significance" was a phrase used in the title of our GRL article. We regarded this as perhaps the most essential point of the article, but it seems to have gotten lost. This is the second of a planned series of notes on spurious significance, to give a sense of the statistical background. Granger and Newbold [1974] posted up here is an extremely famous article, which starts off the modern discussion of the problem of spurious regression. Granger is a recent Nobel laureate in economics. Continue reading →
Sometimes the Hockey Team baffles me. I was at Esper’s website and noticed Esper J, Neuwirth B, Treydte K (2001) A new parameter to evaluate temporal signal strength of tree ring chronologies. Dendrochronologia 19, 93-102. Something that looked pertinent. As a component of his estimate of signal strength, Esper applied a statistical procedure Gleichlàƒ⣵figkeit G which disregarded the number of cores in the sample in a calculation of signal strength. In an important example, the Esper G yields diametrically opposite results to results where the number of cores are considered. Continue reading →
I’ve had a number of requests to explain some statistical topics and tests of significance. I’d rather not get involved in an explanation of general statistical concepts, which are perfectly well covered in many other places. However, I am going to post some notes up on “spurious significance”, which, after all, was part of the title of our GRL article "Hockey Sticks, Principal Components and Spurious Significance", although most of the attention has been spent on principal components. Continue reading →
Climate Audit 