False positive is the idea of getting a result that incorrectly tells you the result is true or correct or positive.
False negative is a result that incorrectly tells you the result is wrong or incorrect or negative.
A great visual at Marginal Revolution: Type I and Type II Errors Simplified.
A few examples from the illustration, life, and auditing:
False positive:
- Telling a man he is pregnant.
- Test result that says you are doing drugs even though it was the sesame seed bagel you ate before the test that triggered the result.
- Concluding there is an error is a sample when the population is actually error-free. Impact? You do unneeded testing to reach a correct conclusion the population is okay.
False negative:
- Telling a woman with a basketball sized bulge at her lower abdomen that she isn’t pregnant.
- Test result that says you are sober even though you are falling-down drunk.
- Concluding a population is okay based on a sample even though there are multiple material errors. Impact? You issue a clean opinion on a materially incorrect financial statement.