Tag Archives: multivariate

Smerdon et al 2008 on RegEM

Smerdon et al 2008 is an interesting article on RegEM, continuing a series of exchanges between Smerdon and the Mann group that has been going on for a couple of years. We haven’t spent much time here on RegEM as we might have. I did a short note in Nov 2007 here. In July and […]

Reconciling to Wahl and Ammann

When Wahl and Ammann’s script first came out, I was able to immediately reconcile our results to theirs – see here. As Wegman later said: when using the same proxies as and the same methodology as MM, Wahl and Ammann essentially reproduce the MM curves. Thus, far from disproving the MM work, they reinforce the […]

Brown and Sundberg: "Confidence and conflict in multivariate calibration" #1

Introduction If one is to advance in the statistical analysis of temperature reconstructions, let alone climate reconstructions – and let’s take improving the quality of the data as the obvious priority – Task One in my opinion is to place the ad hoc Team procedures used in reconstructions in a statistical framework known off the […]

An Example of MBH "Robustness"

In the MBH source code, they apply steps that purport to weight the temperature PCs in their regression calculations proportional to their eigenvalues. Comments on their code say: c set specified weights on data … c weights on PCs are proportional to their singular values This is one of two weighting procedures in MBH for […]

Back from Georgia Tech

First, let me thank me thank Judy Curry for inviting me to make a presentation at their seminar series and for both spending so much time and energy showing me around the department and hosting me so hospitably. I was the guest at many interesting presentations by able young scientists and at splendid lunches and […]

Re-Visiting RegEM: Rutherford et al 2005

Mann et al 2007 is a new RegEM version, replacing the RegEM calculations of Rutherford et al 2005. The logic is not entirely self-contained and so I re-visited some of our previous comments on Rutherford et al here here here here . I’m going to reprise two issues today: Collation Errors, a small but amusing […]

Multivariate Calibration

In calibration problem we have accurately known data values (X) and a responses to those values (Y). Responses are scaled and contaminated by noise (E), but easier to obtain. Given the calibration data (X,Y), we want to estimate new data values (X’) when we observe response Y’. Using Brown’s (Brown 1982) notation, we have a […]

von Storch et al 2004 in IPCC AR4

It’s interesting to see what’s been changed between the Second Draft and AR4 as it went out the door, and compare that to comments. von Storch et al 2004 argued that the low-frequency variance of reconstructions wsa under-estimated, a point with which I agree (although it’s a different point about whether these reconstructions are biased […]

More on "Naturally Orthogonal"

I realize that not all CA readers are interested in multivariate methods and that dendroclimatologists want to “forget the math”, but I find it interesting to try to relate dendro and paleoclimate recipes to known statistical methodologies that you can read about in texts. I commented the other day on the form of Principal Components […]

Nature's Style: "Naturally Orthogonal"?

Wilson and Luckman 2003 observe: The first PCs from the RW and MXD PCA are naturally orthogonal (r = —0.006) over the 1900—1991 period suggesting the in’?fluence of different forcing mechanisms upon these parameters. They move on without pausing here, but this point should not be left without a commentary. The issue here is one […]

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