The cat i' the adage

"The growth of knowledge depends entirely on disagreement" Karl Popper (1902 - 1994)

Friday, January 28, 2005

Passive or active smoking?

Researchers have "told" the British Medical Association that they have found a significant link between lung cancer and passive smoking.

In a study of 123,000 volunteers it transpired that children from homes where parents smoked were three times more likely to contract lung cancer than children with non-smoking parents.

It will be interesting to read the paper when it appears to see how they deal with the obvious confounding factor that the children with smoking parents were more likely to smoke themselves than the children brought up by non-smokers. Have they established that the additional cancers were caused by their parents' smoking rather than by their own? I wonder. I expect the NumberWatcher to be looking closely at this one.

Note also that although 123,000 seems a very large sample, the number of lung cancer incidents was only 97, so expect confidence intervals to be pretty wide.

UPDATE

Here it says that none of the sample had ever smoked, but in the BBC account we learn:

The researchers tracked 123,479 volunteers - some of whom had never smoked, others had stopped smoking, but all had been exposed to second-hand smoke in their childhoods.

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