How Well Do We Understand Probabilities In Medicine?

Posted on July 21, 2016

In his bestselling book, Fooled by Randomness (which was named one of the smartest books of all time by Fortune magazine), Nassim Nicholas Taleb discusses a question that was posed to a group of medical doctors.

A test of a disease presents a rate of 5% false positives. The disease strikes 1/1000 of the population. People are tested at random, regardless of whether they are suspected of having the disease. A patient’s test is positive. What is the probability of the patient being stricken with the disease?

Most doctors answered 95%. Less than one in 5 professionals answered the question correctly.


Fooled by randomness
Taleb, N. (2005). Fooled by randomness: The hidden role of chance in life and in the markets (Vol. 1). Random House Incorporated.
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