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Fun with correlations!

Filed under: — gavin @ 9 May 2007 - (Türkçe)

We are forever being bombarded with apparently incredible correlations of various solar indices and climate. A number of them came up in the excoriable TGGWS mockumentary last month where they were mysteriously ‘improved’ in a number of underhand ways. But even without those improvements (which variously involved changing the axes, drawing in non-existent data, taking out data that would contradict the point etc.), the as-published correlations were superficially quite impressive. Why then are we not impressed?

To give you an idea, I’m going to go through the motions of constructing a new theory of political change using techniques that have been pioneered by a small subset of solar-climate researchers (references will of course be given). And to make it even more relevant, I’m going to take as my starting point research that Richard Lindzen has highlighted on his office door for many years:

That’s right. Forget the economy or the war(s), the fortunes of the Republican party in the US Senate are instead tied closely to the sunspot cycle.

“Oh yes”, the sceptics might say “but that’s just a couple of cycles and doesn’t use up-to-date numbers. What happens after 1986?”

Well, that is a little problematic, however, the good early correlation is obviously still important (r=0.52! 1960-1986) and so we should be able to refer to it over and over again without noting that it breaks down subsequently (cf. Svensmark, 2007 referring to Marsh and Svensmark (2000)). But more importantly, it just demonstrates that the theory needs a little adjustment.

Let’s look at the second half of the record. Well, there’s another strong correlation for that period as well (r=-0.63, 1988-2006). Only this time the correlation is inverted, but that shouldn’t be surprising to anyone – solar-senator effects are complicated!

If we now put it all together, we can see that there is a reasonable match over the whole period…. well, except that break in the period 1984 and 1988 and, unfortunately, last year’s elections didn’t fit the pattern either. But 1984-1988 was Ronald Reagan’s second term and clearly no theory of Republican senators can ignore that. We therefore propose that the ‘Ronald Reagan second term phase shift’ combined with the change of sign of the Hale solar magnetic cycle in 1986, obviously changed the dynamics. This kind of phase shift is frequently seen in solar studies (cf. Landscheidt and many others), where it is rarely taken as a sign that two time series with decadal spectral power are in fact completely independent. Finally, it is permissible to leave off the more recent data points (cf. TGGWS) for “graphical convenience”. So after just a little work, we have managed to rescue the original theory to match a much longer amount of data:

Some readers may scoff and suggest that in the absence of any mechanism, these powerful correlations are numerological artifacts arrived at using post hoc fallacious reasoning that have no predictive capability. That might appear to be a valid argument. However the ultimate test will of course be experimental. On the basis of these intriguing results, we propose exposing Republican senators to varying levels of cosmic rays in a basement and monitoring their electability. Any refusal by the funding agencies or ethical review panels to support this would simply be confirmation that the political science establishment are scared of what this research would imply for their so-called “consensus”.

Convincing, eh?

The data for sunspots and senators can, I’m sure, be manipulated even more effectively than I’ve done here. I’ve made no use of various lags or filters (which can be altered as you go along cf. Friis-Christensen and Lassen (1991)), or of partial detrending (cf. Marsh and Svensmark (2003)), or of splicing of unconnected data sets (cf. Svensmark and Friis-Christensen 1997, Nir Shaviv). More ideas could be taken from “New evidence for the Theory of the Stork” (Höfer et al, 2004)”. A special RealClimate commendation for anyone who can do better!

356 Responses to “Fun with correlations!”

  1. 351

    Hmmm, … OK … explicit link in #349 above that this forum mysteriously screws up – looks like a deficiency in the even more mysterious “” wotsit thing:

    Screwed up link:

    In context appearance of link:

    ” …

    P.S: Are the “resident” gurus who contribute here, just naturally rude, or just really really busy? I asked what I thought were some reasonable questions ages ago in another RealClimate forum, and after just one other not very helpful and really not too sensible reply that seemed to completely ignore enthalpies of formation, etc. that forum was shut down for further posts – and thereby any answers to the questions posed there that I could easily find. Any chance anyone here can address the questions there?

    I’m busy too, so can’t be bothered re-formatting the post, so here’s the [explicit] link to it:

  2. 352
    Hank Roberts says:

    Mr. Revell asked in the other thread a lot of questions. You can find most answers to FAQs with the search box, top of the page.
    > who has entered, R. Branson’s Virgin Earth Challenge
    Try his website or Google
    > Anybody know where I can get a [reference mentioned] – I mean without having to pay?
    Ask your local public library Reference Desk; if not available, they will be able to borrow a copy via interlibrary loan.
    >How do you get an article/paper published here?
    None are. See Contributors’ links on right side for their publications.

    Most of us posting here are just interested readers.

  3. 353
    PHE says:

    So, my comments do not ‘pass the test’. In any case I suggest you read Three Men in a Boat by Jerome K Jerome. That’ll cheer you up. The future’s not so bad.

  4. 354
    Timothy Chase says:

    PHE (#353) wrote:

    So, my comments do not ‘pass the test’. In any case I suggest you read Three Men in a Boat by Jerome K Jerome. That’ll cheer you up. The future’s not so bad.

    The future?

    I am still hoping that it hasn’t been written yet – or at least not the last few chapters of it. But if I need some cheering up or just wish to enjoy myself for a short time, Babylon 5 generally does the trick for me. At this point I think I will spend some time with G’Kar, Londo and Vir. Or maybe I will watch the first movie.

  5. 355

    Hank, the time scale for the first two is on their axis (doesn’t read well-agreed), and is between 1000 to ~2000 AD. This link is working

  6. 356
    Aaron F. says:

    Re. #38:

    As for physical models, George Box said, “All models are wrong, some models are useful.” A classic recent example in supernova SN2006gy, the largest supernova ever observed, which fell outside the standard models of supernovae explosions (and provided physical evidence for an alternative model, the “pair instability model”).

    You give the impression here that there are several competing “standard models” that all propose to explain the single phenomenon of supernovae, but that isn’t how supernova science works. There are many different types of supernovae, and some have very different physical causes than others. SN2006gy is evidence not for an “alternative model,” but for a new type of supernova that has been proposed before, but never observed (until, perhaps, now).

    Just wanted to set the record straight!