Doctors flunk quiz on screening-test math

By Tom Siegfried, 18:22 PM April 22, 2014

Imagine a hypothetical baseball player. Call him Alex. He fails a drug test that is known to be 95 percent accurate. How likely is it that he is really guilty?

If you said 95 percent, you’re wrong. But don’t feel bad. It puts you in the company of a lot of highly educated doctors.

OK, it’s kind of a trick question. You can’t really answer it without knowing some other things, such as how many baseball players actually are guilty drug users in the first place. So let’s assume Alex plays in a lea...

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