For example, if your two risks are 0.01% and 0.02%, the risk ratio is 2 and the odds ratio is: (0.02/99.98)/(0.01/99.99) = 2.0002 Barely different
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But if the two risks are 20% and 40%, the risk ratio is still 2 (40/20) but the odds ratio becomes VERY different: (40/60)/(20/80) = 2.67 That's a lot higher!pic.twitter.com/73Fc7CxeUU
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Going back to this headline that I picked up - it looks at a study that used logistic regression, which spits out odds ratiospic.twitter.com/8vHaEBaLIS
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The results were reported as odds, with vapers having a 1.83 times higher odds of stroke than non-vapers Given that the prevalence of stroke was 2-4% in the groups, that means that the risk ratio would be a bit lower than 1.83
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In other words, the headline rounds UP from 83% to a 100% increase (double), but in actual fact it's more likely that the risk is somewhere around 75% instead!
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And this is done almost ubiquitously across the board It's not really the media's fault - scientists do it all the time as well!pic.twitter.com/BjxCDlughU
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It's also really hard to tell if the study used risks or odds unless you actually read it, which adds a layer of complexity to the matter
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Honestly, I want to end on a nice easy note, but the fact is that odds are confusing, a lot of researchers get them wrong, and it's unlikely we'll have a solution to this any time soon Hurray!
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Anyway, a reasonable proportions of the headlines you've seen probably overestimate the actual risk because the studies used odds ratios
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It depends, but often yes
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