Naked Science Forum
General Science => General Science => Topic started by: Jessica H on 05/11/2010 15:27:05
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The idea that correlation does not imply causation is sometimes hard to get across. Has anyone read any interesting studies that suggested a link that ended up not being a direct cause and effect realtionship?
I've used the example before about the study that suggests Diet drinks "cause" you to gain weight.
http://www.foxnews.com/story/0,2933,159579,00.html
But there could be a cause and effect relationship there if diet drinks cause you to crave sugar, so perhaps it's not the best example.
Any other ideas?
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The classic one that epidemiologists often teach in medical school is the apparent link between coffee and pancreatic cancer. But more careful analysis reveals that people who drink coffee are more likely to smoke and it's actually the cigarette that accompanies the coffee that causes the cancer, rather than the coffee. At least, I hope that's the case, otherwise I'm in trouble, given my coffee fetish...
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My favourite example is that, if you look at the size of children's feet and how well they do in arithmetic tests, it seems that the keep their brains in their feet.
There's a strong correlation between foot size and ability to do arithmetic.
Of course, it's not causation; both measured variables are strongly correlated with the age of the children. Older ones have bigger feet and better maths.