Comments on: Mo' Mo' Moberg

By: Sampling from Contaminated Distributions « Climate Audit

Sampling from Contaminated Distributions « Climate Audit — Sun, 01 Jul 2012 15:53:59 +0000

[...] Update: Here are qqnorm plots for Moberg previously posted up here [...]

By: TCO

TCO — Sun, 11 Jun 2006 22:53:02 +0000

1. Yes. He’s worse then you. What do you want? A prize?
2. You divert occasionally.

By: Steve McIntyre

Steve McIntyre — Sun, 11 Jun 2006 20:38:37 +0000

My comment was an “aside” in the sense that I was making a substantive point and said something in passing. Rasmus’ point was not an “aside”, but a diversion and about 2 other logical fallacies.

By: TCO

TCO — Sun, 11 Jun 2006 18:47:00 +0000

Yes Rasmus’s remark is an aside. I have had to correct you for some asides and such as well, Steve.

Anyway, at least you understand where he got the grist for the remark from now. I will spare you from a contracts lawyer discussion of should, must, may, shall, will and the like.

By: Steve McIntyre

Steve McIntyre — Sun, 11 Jun 2006 18:07:39 +0000

#56. I think that there's a distinction to be drawn between my phrasing that it's "much more in keeping with the data" than saying that a discrete wavelet transform "should" be used. The basis for that opinion is just that the plots here are more informative (to me anyway) than the continuous wavelet. I dislike methods that appear to produce thousands of data points as implied by each color of a CWT diagram when you're starting with a series with a few hundred data points only. But this is hardly a central point for me. I didn't articulate that in this post, since I was more interested in showing what Moberg series looked like under a DWT. I don't believe that any rational person would argue that these graphs are not more informative than anything that you've seen elsewhere on this data set. But the context in which this arose is even more illuminating. Look at how Rasmus presents this over at realclimate: A poster pointed out that I'd said of VZ shown with Rasmus reply):

VZ did not analyze the impact of the MBH98 method on MBH98 proxies and, since their replication of MBH98 methods was flawed, does not show that problems with MBH98 PC methodology did not matter." [Response: I have also read a number of posts on climateaudit.org, and I think that a large fraction of what it has to say is mumbo-jumbo. Take for instance the statement that since they used an annual mean value, they should use discrete wavelet anaysis (post on Moberg's work). This doesn't make sense. Furthermore, it has a go at the iid-test, but without making any point - just insinuations. To my mind, one of the classic examples of how they twist the logic can be found in Are Temperature Trends affected by Economic Activity?. -rasmus]

Rasmus does not rebut the actual point. Instead of dealing with whether VZ had analyzed the impact on MBH, Rasmus picks at a tangential point buried halfway down in one of over 300 posts here. Then he brings up a paper that I had nothing to do with. All too typical.

By: TCO

TCO — Sun, 11 Jun 2006 14:37:55 +0000

All of these series are annual series and so a discrete wavelet transform is much more in keeping with the data.

This is what Rasmus reacted to.

By: mark

mark — Tue, 01 Nov 2005 06:25:05 +0000

My guess is that a CWT requires some sort of curve fitting to the original data to generate an equation describing the set. Then a CWT can be performed… but wouldn’t that introduce some large errors in the first place?

Mark

By: TCO

TCO — Tue, 01 Nov 2005 05:34:23 +0000

Those guys are so frigging touchy, that they are gunning for you even when you are just trying out analyses. Don’t pay any attention to that and keep trying things.

By: Steve McIntyre

Steve McIntyre — Tue, 01 Nov 2005 04:36:45 +0000

Re #51: Rodrigo, sorry I missed your inquiry. I did these charts with an LA8 wavelet. I just did them to see what they looked like. There are some obvious end effects that would need to be dealt with and if I return to the topic in a more complete way, I’ll look at this.

Re #52: Rasmus at realclimate misquoted and slagged me in respect to my use of discrete wavelets here. He said that I claimed that discrete wavelets “should” be used because the data is annual, a claim which he said made no sense. I obviously didn’t say that there was any obligation to use discrete wavelets; on the other hand, I find the information about the proxies in the discrete graphs above to be more helpful than the CWT wavelet diagram illustrated in Moberg. I don’t see anything wrong with that.

By: mark

mark — Tue, 01 Nov 2005 04:15:22 +0000

GregF, wavelets are not necessarily bandpass filters. The wavelets I studied for my MS thesis were actually akin to quadrature mirror filters, i.e. high/lowpass pairs. Each stage of a decomposition took the lowpass side and filtered with another pair. The result was a bank of successive high pass outputs and a final high/lowpass pair.

Either way, I’m unsure how one would go about implementing a true CWT using discrete data.

Mark