- For people that really do have the allergy, a test says "Yes" 80% of the time - For people that do not have the allergy, a test says "Yes" 10% of the time ("false positive") Here it is in a table: Test says "Yes" Test says "No" Have allergy 80% 20% "False Negative" Don't have it 10% "False Positive" 90% If 1% of a population has the allergy, and 1000 people are tested: How many people have the allergy? How many of these people tested positive? (True Positive) How many people who did not have the allergy, were told that they did? (False Positive) Therefore, how many people received a positive test result