Base Rate Fallacy
quote
What you haven't considered is how the results depend on the base rate of the percentage of drunk drivers. Consider the scenario where everyone makes the right decision, and no one ever drives drunk. In this case the probability that a person is sober is 100 percent, regardless of what the Breathalyzer test results say. When a probability calculation fails to account for the base rate (like the base rate of drunk drivers), the mistake that is made is called the base rate fallacy.
From
Chapter:
Lies, Damned Lies, and Statistics
Section:
It Depends