Gordian Knot of Nonsense – Part 6. Irrelevance of Baysian Analysis

It has been a while since I wrote about ”Climate related sea-level variations over the past two millennia” (Andrew C. Kemp, Benjamin P. Horton, Jeffrey P. Donnelly, Michael E. Mann, Martin Vermeer, and Stefan Rahmstorf, PNAS, 2011), which I will refer to as KMVR2011.

Please see this index of my posts concerning KMVR2011.

I want to sew up one loose end here.  Last time around I showed that this latest incarnation of the Rahmstorf model relating sea level to temperature was just as bogus at the previous versions. But I did not talk about one of their interesting (but ultimately irrelevant) new twists. Another layer of complexity was added by the application of Bayesian analysis, or in KMVR2011 nomenclature: “Bayesian multiple change-point regression.”

Bayesian analysis is a useful, but often counter intuitive, statistical method to tease out an underlying distribution from an observed distribution. That being said, the KMVR2011 application of Bayesian analysis starts out with a bogus model, which has been demonstrated ad nauseam. (See here and here.)  This added layer of complexity simply obfuscates the failures of the starting model, rather that addressing those failures.

My next series of posts will move on to another recent outing by Rahmstorf and company – Testing the robustness of semi-empirical sea level projections  (Rahmstrof, et. al., Climate Dynamics, November 2011)

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