Category Archives: Mann et al 2008

Replication Problems: Mannian Verification Stats

If anyone feels like sticking needles in their eyes, I’d appreciate assistance in trying to figure out Mannian verification statistics. Even when Mann posts up his code, replication is never easy since they never bothered to ensure that the frigging code works. Or maybe they checked to see that it didn’t work. UC’s first post […]

Can’t See the Signal For the Trees

ABSTRACT: A new method is proposed for determining if a group of datasets contain a signal in common. The method, which I call Correlation Distribution Analysis (CDA), is shown to be able to detect common signals down to a signal:noise ratio of 1:10. In addition, the method reveals how much of the common signal is […]

A New Caramilk Secret

Jean S, UC and I spent a considerable amount of time a couple of years ago, trying to figure out how MBH99 confidence intervals were calculated – see here. I asked the NAS panel to investigate the matter, but they failed to do so. After their report, I asked NAS president Cicerone to merely write […]

The Rain in Spain

Erroneous geographical locations of precipitation proxies have been source of mild amusement to CA readers. Long ago, in connection with MBH, we observed that the rain in Maine fell mainly in the Seine – an error that Mann stubbornly refused to correct in Mann et al 2007 – not that any reviewer cared. A few […]

A Surprising Result

Yesterday, I observed some seemingly bizarre patterns in Mannian splicing, which seemed at first to be an inexplicable stupid pet trick. However, in this case, what seems to be a stupid pet trick appears to implement an intentional Mannian procedure referred to in passing in the SI, but not shown in the online source code. […]

More Stupid Pet Tricks

Yesterday I left my exposition of Mannian CPS just before trying to do a NH composite. There was another stupid pet trick left, that made replication of this step a little trickier than one would think. UC had sent me a file entitled NHmean.txt (which I’ve placed online), which was produced during gridboxcps.m, and proved […]

Mannian CPS: Stupid Pet Tricks

David Letterman sometimes has a segment entitled “Stupid Pet Tricks”, which is an apt title for today’s post – more parsing of Mannian CPS, recently discussed here. With helpful contributions from Jean S, UC and Roman M, I can now pretty much replicate Mannian CPS, but only through a variety of devices that fall into […]

Mannian CPS

As a technique, CPS is little more than averaging and shouldn’t take more than a few lines of code. You standardize the network – one line; take an average – one more line; and then re-scale to match the mean and standard deviation of your target – one more line. (I’m not commenting here on […]

More on the Gridded MXD Data

We’ve noted that Briffa’s gridded MXD has high correlations to temperature, much higher than run-of-mill proxies. We’ve also noted that Mann (like Briffa) truncated this data at 1960 because of divergence. At the time that Mann et al 2008, the gridded MXD data was not available anywhere – Mann cited a webpage as follows: The […]

If Nychka Standards Applied to Mann…

Santer et al 2008 (including realclimate’s Gavin Schmidt) sharply criticized Douglass et al for failing to properly consider the effect of autocorrelation of regression residuals on trend confidence intervals, which they described as a “methodological error”. The need to properly account for autocorrelation in confidence interval estimation is a fairly long-standing theme at CA and […]