ABSTRACT
The following question was once asked of 60 staff and students at the Harvard Medical School: “If a test to detect a disease whose prevalence is https://www.w3.org/1998/Math/MathML" display="inline"> 1 1000 https://www.w3.org/1999/xlink" content-type="black-white" xlink:href="https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429151385/e1d3cc54-b374-4dc6-940a-77448f552eef/content/math21_401_1_B.tif"/> has a false positive rate of 5%, what is the chance that a person found to have a positive result actually has the disease, assuming you know nothing about the person’s symptoms or signs?” 1
