Positive and negative predictive values

Positive and negative predictive values are terms that describe how well a test or prediction can accurately predict something. Positive predictive value is the proportion (or percentage) of people who have a positive result on a test who actually have the condition or thing they are being tested for. Negative predictive value is the opposite - it is the proportion (or percentage) of people who have a negative result on the test but do not have the condition or thing they are being tested for.

Think of it like a game. Positive predictive value is when you guess the right answer and you get it right. Negative predictive value is when you guess the wrong answer and you get it right.