Mathematical
False Positive Paradox
A highly accurate test can still be wrong most of the time
Overview
A counterintuitive result where a 99% accurate test for a rare condition still produces mostly false positives.
A disease affects 0.1% of people. A test is 99% accurate. You test positive. What's the probability you have the disease? Intuition says 99%, but it's actually around 9%. Most positive results are false because the disease is so rare.