Category Archives: Statistics

New Paper by McKitrick and Vogelsang comparing models and observations in the tropical troposphere

This is a guest post by Ross McKitrick. Tim Vogelsang and I have a new paper comparing climate models and observations over a 55-year span (1958-2012) in the tropical troposphere. Among other things we show that climate models are inconsistent with the HadAT, RICH and RAOBCORE weather balloon series. In a nutshell, the models not only […]

Screening Proxies: Is It Just a Lot of Noise?

There has been a great deal of discussion on a recent CA thread on the efficacy of screening proxies for use in reconstructions by selecting on the size of the correlation between the proxy and the temperature during the calibration time period. During the discussion I asked Nick Stokes the following questions in a comment: […]

Chladni and the Bristlecones

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 […]

Calibrating “Dr. Thompson’s Thermometer”

One of the most persuasive images in the global warming debate is a graph that Al Gore describes in his An Inconvenient Truth as “Dr. Thompson’s thermometer.” According to Gore, this graph is based on oxygen isotope ratios from ice cores collected by Lonnie Thompson and his colleagues, and provides “the most definitive” independent confirmation […]

The Lodgepole Pine: A Case Study

Every year, the Statistical Society of Canada has a case study competition for statistics students in Canada. The problem and the data are posted about six months before the annual meeting. Teams of students analyze the problem and then present their results at a poster session at the meetings. One of the two topics for […]

Spline Smoothing

The 2009 Climate Dynamics paper “Unprecedented low twentieth century winter sea ice extent in the Western Nordic Seas since A.D. 1200” by M. Macias Fauria, A. Grinsted, et al. discussed already on the thread Svalbard’s Lost Decades pre-smooths its data with a 5-year cubic spline before running its regressions. There’s been a lot of discussion […]

Rejected … by RC!

I have been rejected at RealClimate! My first rejection! I have not posted there in about two years although I have occasionally read some of their consensus defences when they were relevant to what I have been looking at. They have been running a Steig Corrigendum thread concurrent with ours and I have followed it […]

Why did Steig use a cut-off parameter of k=3?

A question that Jean S inquired about before we were so rudely interrupted. The expanation in Steig et al was: Principal component analysis of the weather station data produces results similar to those of the satellite data analysis, yielding three separable principal components. We therefore used the RegEM algorithm with a cut-off parameter k=3…. A […]

RegEM PTTLS Ported to R

I’ve now ported my emulation of Schneider’s RegEM PTTLS to R and benchmarked it against Jeff’s Matlab as shown below. I caution readers that this is just an algorithm. There are other ways of doing regressions and infills. The apparent convergence to three PCs noted by Roman is still pending as a highly interesting phenomenon. […]

Porting RegEM to R #1

I’ve transliterated relevant Tapio Schneider code into R (pttls.m) and parts of regem.m that seem relevant at present. Jeff Id has extracted a variety of intermediates from his Matlab run and I’ve fully reconciled through two steps with remaining differences appearing to be probably due to transmission rounding. My dXmis statistic at step one was […]