In the ES&T article, Jerry Mahlman, rather than using ad hominem techniques like discussing biases in principal components methodology, spurious significance of RE statistics or the validity of bristlecone pines as temperature proxies, described us simply as "quacks".
We start our consideration of the use of the technical term "quack" in climate science through the remarkable iconography of von Storch’s recent presentation in Boulder.
The iconography has a long story, even involving the Wall Street Journal, and shows a pleasingly humorous side to Prof. von Storch. Continue reading →
One of the points made by ES&T to supposedly marginalize the Wall Street Journal article was:
Although most other U.S. newspapers, with the notable exception of the New York Times, also provide minimal coverage of climate change studies in science journals, ES&T found no other newspaper that reported on the McIntyre and McKitrick article.
The suggestion that there has been a lack of media interest in our research is a curious place for ES&T to stand and the claim that "no other" newspaper reported article on the article does not say very much for ES&T research competence. Perhaps they got Naomi Oreskes to do their literature search. Continue reading →
There’s a long article in Environmental Science & Technology about the proprietor of this blog (thanks to Dano for the reference) . Continue reading →
Chas. has sent in a recipe for showing random walks in Excel. These sorts of things are much, much easier in R (see http://www.r-project.org for free download). I’ve posted up a little script below which generates random walks and ARMA(1,1) walks together with trend lines and t-statistics. Continue reading →
For the several people who’ve asked that the autocorrelation comments be collected, I’ve added a Category labelled “Spurious” in the right sidebar. When I get some time, I will update the Categories as they are a useful way of keeping track of things.
This article was brought to my attention by Larry Huldén. It is a memorandum written by Professor Paul Reiter to the UK House of Lords on the widely disseminated idea promoted by the IPCC that climate change will produce increased ranges for mosquito-borne diseases such as malaria and dengue fever.
If people are in any doubt as to the true nature of the IPCC’s "scientific consensus" then Professor Reiter removes that doubt.
Continue reading →
I’ve recently run across an article on changing water use efficiency in bristlecones, which pretty much put the nail in the coffin on any lingering ideas that 20th century bristlecone ring widths might be a temperature proxy. Tang et al. [1999], "The dC13 of tree rings in full-bark and strip-bark bristlecone pines in the White Mountains of California", shows a remarkable non-climatic increase of dC13 ratios of bristlecones at Sheep Mountain, the most important site in the MBH98 PC1. The dC13 values are stated to show an equally remarkable nonclimatic increase in water use efficiency at Sheep Mountain. Improved water use efficiency was the predicted mechanism for CO2 fertilization. See their Figure 3 below. Any attempt to argue that bristlecones are a temperature proxy on scientific grounds (something that has been conspicuously absent from any response by realclimate or their associates) would need to adjust for non-climatic changes in dC13 ratios and water use efficiency. Continue reading →
I’ve been posting up on some fundamental articles on spurious regression, involving autocorrelated processes. Here are some illustrations of what different examples look like, with specific comment on a realclimate article. Continue reading →
Science has recently weighed in with an editorial in which the editor of Science, Donald Kennedy, stated that he is “outraged” by the Barton Committee inquiring into processes for due diligence and disclosure in connection with science being applied for large-scale public policy. I thought that people might be interested in an account of my experience with Science in trying to obtain underlying data from Lonnie Thompson’s ice core studies, regularly published in Science. Continue reading →
I will go approximately 50-50 for a while on posting statistical and non-statistical notes. Today’s another statistical note. It’s a bit technical, but some of the statistical findings from econometrics on autocorrelated series are highly applicable to climate and, while there is occasional citation of econometric literature in climate articles and occasional forays by econometricians into climate, the diffusion seems very incomplete at present, with climate scientists often using quite (in my opinion) naive and inadequate techniques. So I’m trying to bring some statistical findings on the impact of autocorrelation to the attention of people interested in climate series.
I’m learning some of this as I go, so I’m just a one-eyed man here. Some references have been sent to me on earlier notes and I’ll comment on most of them a little later, after I get review a couple more papers. I’m also going to return to the specific examples of spurious significance cited in our GRL article – the extraordinarily high RE statistics from simulated PC1s combined with insignificant R2 statistics.
One of the reasons for discussing Granger-Newbold and Phillips is to show their approach to "spurious" regression statistics (here t-statistics and F-statistics) and why other statistics need to be considered to ensure that there is no mis-specification in the model. In the case of our MBH98 critique, we argue that it is the RE statistic that is spurious and that the R2 statistic, in this case, provides a cross-check. In the examples below, it is the t- and R2 statistics that are spurious and the DW statistic is a cross-check. The point is the need for care and due diligence, rather than magic bullets. Perhaps the discussion of Phillips and other texts on spurious signifiance will also illuminate the approach that we used in our GRL article and why we discuss "spurious significance" Continue reading →
Climate Audit 
Von Storch and the Mighty Ducks
In the ES&T article, Jerry Mahlman, rather than using ad hominem techniques like discussing biases in principal components methodology, spurious significance of RE statistics or the validity of bristlecone pines as temperature proxies, described us simply as "quacks".
We start our consideration of the use of the technical term "quack" in climate science through the remarkable iconography of von Storch’s recent presentation in Boulder.
The iconography has a long story, even involving the Wall Street Journal, and shows a pleasingly humorous side to Prof. von Storch. Continue reading →