Tuesday, January 10, 2012

Heaven's Department of Epidemiology

Watch out for risk's magnifying glass - and cut your risk of being tripped up by 82%!

Whenever you see something tripling - or halving - a risk, take a moment before you let the fear or optimism sink in.

Relative risks are critically important statistics. They help us work out how much we might benefit (or be harmed) by something. But it all depends on knowing your baseline risk - your risks to start with.

If my risk is tiny, then even tripling or halving it is only going to make a minuscule difference: a half of 0.01% isn't usually a shift I'd even notice. Whereas if my risk is 20%, tripling or halving could be a very big deal. Unless you know a great deal about the risks in question - or your own baseline risk, you need more than a relative risk to make any sense out of data.

There's a good introduction to absolute and relative risks at Smart Health Choices

This is one of the 5 shortcuts to keep data on risks in perspective, at Absolutely Maybe.

Cartoon and content updated on 3 June 2017: This post was originally the cartoon only, from my blog post for the British Journal of Sports Medicine.

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