The significance of agnotology

A year or so ago, there was a lot of fuss around the talking point, originating with Richard Lindzen of MIT that “There has been no statistically significant warming since 1995?”At the time, I observed that this meant nothing more than “given the variability in the data, we need at least 15 observations to reject the null hypothesis at 95 per cent confidence”. Thus, it was totally unwarranted to slide, as Lindzen and others did, from “no statistically significant warming” to “no significant warming” or even, in Lindzen’s case “warming has ceased for the past fourteen years”. Sad to say, most of the “sceptics” who profess to “make up their own mind” on the issues, are either too lazy or lack the mental equipment to learn the basic statistics needed to understand this point, and therefore unthinkingly repeated Lindzen’s claim. But, to anyone who understood the issues, it was obvious that a couple more observations in line with the observed warming of recent decades would be enough to bring the trend to statistical significance.

With 2010 over, we now have 16 observations starting in 1995, and (unsurprisingly to anyone who followed the argument thus far) the upward trend is now statistically significant at the 5 per cent level[1] That is, if climate change since 1995 (the time of the first IPCC report, and well after Lindzen announced himself as a sceptic) had been purely random, the odds against such an upward trend would be better than 20 to 1 against.

The obvious question is whether Lindzen will now concede that his claim, and the inference he drew from it, has been falsified, and that warming has not in fact ceased as he suggested. I’m willing to bet that what we see is evasion, obfuscation of or outright silence, not only from Lindzen, but from all of those who parroted his claim.

fn1. My estimates based on the Hadley data used by Lindzen gives an estimated trend of 0.012 degrees a year, with a t-value of 2.45.

300

Victoria suffered just under 300 deaths in road crashes in 2010. That’s a tragedy nearly every day, but it’s still a small fraction of the toll exacted by motor vehicles 40 years ago, when the road toll peaked at 1061 in 1970 (at at time when there were fewer people and many fewer cars). I couldn’t find a graph for Victoria but here is one for Australia as a whole, showing the same pattern with a slight lag as other states followed Victoria.

Anyone my age or older will remember that, after decades of accepting steadily increasing death rates as the price of mobility, Victorian governments of both political persuasions finally took the politically courageous step of enforcing higher safety standards – first seat belts and automative design rules, then effective techniques to catch and convict speeders and drink drivers, then helmet laws and more stringent license testing, among many others. Victoria’s interventions were eventually followed by other governments in Australia and elsewhere, but the lags are such that Victoria has gone from having some of the most dangerous roads in the world to having some of the safest. Nevertheless, and not surprisingly, these steps aroused plenty of opposition at the time, and the opponents were able to produce supposed experts to back their arguments.

What might seem more surprising is that even after four decades in which their claims have been refuted beyond any reasonable doubt, the same experts are still pushing the same discredited lines, and still finding a ready audience. With a closer look at the experts and their audience, this fact is perhaps less surprising, but still requires some explanation.

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Sandpit 300

This is a sandpit for people who want to
(a) argue about the efficacy of specific road safety interventions
(b) record their status as believers (with or without qualification) in the libertarian/conservative orthodoxy that climate change is a hoax/fraud/unsupported hypothesis.

I’d request no responses to those in category (b). They are, in my view, beyond help, and there are plenty of sites pointing out their errors if they want to look.

Goodbye 2010

Well, 2010 is over and it’s been a year of contradictions for me. In personal and family terms, things have gone very well, starting with the birth of my first grandson, James in March. Then there’s my literary offspring Zombie Economics, which seems to be going very well, and my election as a Fellow of the Econometric Society (quite a big deal in the academic circles where I move, if not exactly a barbecue-stopper among family and friends in general).

Politically on the other hand, it’s been a year of frustration.

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