Sound familiar? There are enough examples of confusing absolute and relative risk that we could stay in business here if we wrote about nothing else.
Today's Exhibit A: A story last week in the UK's Daily Mail that says women who use hormone replacement therapy for an extended time have a risk "as high as 70 percent" of developing a brain tumor known as a meningioma. Horrible, if true.
But of course it isn't. "According to our results, the risk of developing meningioma may be increased by a factor of 1.7 in women taking HRT for 10 or more years, compared with women that do not take HRT," said David Gaist of the University of Southern Denmark. He was the senior author of the study that prompted the Daily Mail's report.
"This of course does by no means translate into the statement quoted in the newspaper article," Gaist said in an email.
The absolute risk is small; the relative risk is significant.
This has been a public-service announcement. We now return to your regularly scheduled programming.
-Paul Raeburn
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