Quotulatiousness

December 20, 2010

Once again, correlation is not causation

Filed under: Britain, Media, Science — Tags: , , — Nicholas @ 12:50

An excellent example of what statistical analysis can and cannot show:

Do mobile phone towers make people more likely to procreate? Could it be possible that mobile phone radiation somehow aids fertilisation, or maybe there’s just something romantic about a mobile phone transmitter mast protruding from the landscape?

These questions are our natural response to learning that variation in the number of mobile phone masts across the country exactly matches variation in the number of live births. For every extra mobile phone mast in an area, there are 17.6 more babies born above the national average.

This was discovered by taking the publicly available data on the number of mobile phone masts in each county across the United Kingdom and then matching it against the live birth data for the same counties. When a regression line is calculated it has a “correlation coefficient” (a measure of how good the match is) of 98.1 out of 100. To be “statistically significant” a pattern in a dataset needs to be less than 5% likely to be found in random data (known as a “p-value”), and the masts-births correlation only has a 0.00003% probability of occurring by chance.

Part of the problem is that our brains have evolved to detect patterns and relationships — even when they’re not really there:

Mobile phone masts, however, have absolutely no bearing on the number of births. There is no causal link between the masts and the births despite the strong correlation. Both the number of mobile phone transmitters and the number of live births are linked to a third, independent factor: the local population size. As the population of an area goes up, so do both the number of mobile phone users and the number people giving birth.

The problem is that our first instinct is to assume that a correlation means that one factor is causing the other. While this does not cause a problem when using pattern-spotting as an evolved survival tool, it does cause severe problems when assessing possible health scares based on a recently uncovered correlation. For the majority of cases, correlation does not indicate the presence of causality.

H/T to Maggie Koerth-Baker for the link.

Boris trims his sails

Filed under: Britain, Environment, Politics — Tags: , , , , , , — Nicholas @ 07:56

James Delingpole has a bit of fun at London mayor Boris Johnson’s expense:

. . . what sounds like a fervent declaration of faith in the Warmist creed may on closer examination be a perfectly innocuous statement of the bleeding obvious cunningly calculated to appease all Boris’s rentseeking chums in the City who stand to make a fortune from the Great Carbon Scam and would be most displeased if the Mayor of London were to show signs of wobbling.

Yet wobbling is, of course, exactly what Boris is doing. Or rather — remember, this is the man so ambitious he makes Alexander The Great look like Olive from On The Buses — he is slyly repositioning himself to take advantage of the inevitable collapse of public faith in the Great Anthropogenic Global Warming Ponzi Scheme.

All those thousands of people who’ve had their Christmas ruined as a result of Heathrow airport’s pathetic inability to operate in the snow; all those thousands who have been stranded shivering for eight hours at a stretch on our motorways; all those thousands who can’t use their local municipal sports club because the staff — as is the wont of public sector workers — can’t be bothered to allow themselves to be inconvenienced by the inclement conditions; all those people who are going to look at their electricity and gas bills come the end of next quarter and be appalled beyond measure by how increasingly unaffordable they are; all those businesses big and small whose profits are going to be seriously dented by our political class’s ongoing failure to address our transport infrastructure (and no I don’t mean the irrelevant high-speed rail link to Birmingham; I mean the much bigger problem of our shortage of runways at the airports serving London).

All these thousands of people add up to a lot of disgruntled voters ready to ask hard questions about everything from the size of the state (so patently NOT being shrunk to any significant degree by Cameron’s useless Coalition of the Unwilling) to the three main parties’ position on “Global Warming”.

“The typical budgeting strategy of most Canadians is 1. Get paid 2. Spend it all 3. Borrow more.”

Filed under: Cancon, Economics, Politics — Tags: , — Nicholas @ 07:50

Kelly McParland looks at the efforts of the Canadian and provincial governments to come to some sort of agreement over pension reform:

If you want a hint of the difficulty of winning agreement on an issue like Canada’s creaking pension system, consider this carefully considered statement from Finance Minister Jim Flaherty:

“It’s a multi-jurisdictional challenge to get a consensus on the CPP,” he said.

If you speak politics, you realize that “multi-jurisdictional challenge” means that getting the country’s federal and provincial leaders to agree on anything beyond what time to quit for lunch is beyond the power of mere mortals. It is especially hopeless on an issue as fraught with electoral danger pensions, which, after all, are all about old people and their money. Who votes in far bigger numbers than any other demographic? Old people. What gets them more excited than half-price fares to Florida? Their money.

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