Daily bias in the mail

David Spiegelhalter writes in his blog about this news headline on the Daily Mail (DM)’s website. According to the article, statins can weaken muscle and joints, raising the problem by up to 20%. As David points out, this claim is not justified by the evidence in the original article, since the DM is actually mixing up the meaning and interpretation of odds ratio and relative risk.

So, in truth, the actual absolute difference in the risk of having muscle and joints problems is merely 2% (extra risk for those using statins). And even then, all sorts of additional problems arise (eg, again as pointed out by David, the fact that individuals taking statins are more likely to be under constant observation and information about their overall health status more likely to be recorded).

But what’s also interesting, I think, is the confirmation bias in most of the comments to the article on the DM’s website. Many of those who bothered: a) reading the article; and b) commenting (which of course in itself does not make for a very representative sample!), confirmed that they too had problems which by now they can assert with absolute confidence are due to consumption of statins!

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