https://en.wikipedia.org/wiki/Positive_and_negative_predictive_values https://en.wikipedia.org/wiki/Positive_and_negative_predicti... If the number of true pos

https://en.wikipedia.org/wiki/Positive_and_negative_predictive_values https://en.wikipedia.org/wiki/Positive_and_negative_predicti... If the number of true positives is 10/1000, and the test gives you 11/1000 positive results, then 1/11 of your tested positive results are false positives. (Actually closer to 9% than 10%).