Can you tell me which of the following is an example of a true negative outcome?
1. Mary's pregnancy test came back negative, but she is actually pregnant
2. Joe's car was clocked speeding by a radar gun while he was going faster than the posted speed limit
3. Anna failed an exam because she hadn't learned the information it covered
4. Tony's strep test came back negative, but he didn't recover without antibiotic treatment
In all of these cases, we are doing some sort of test. We are asking a yes or no question and trying to answer it with our test. In Option 1, we ask if Mary is pregnant. In Option 2, we ask if Joe was speeding. In Option 3, we ask if Anna knew the information covered by the test. In Option 4, we are asking whether Tony has strep throat. All of these can be answered with a “yes” or a “no.” In addition, it is possible for the test to give a correct result or an incorrect result. A true negative outcome exists when the test gives a negative answer to the question and when that answer is actually accurate. Only Option 3 fulfills these conditions.
In Option 1, the test did give a negative answer to the question of whether Mary was pregnant. However, it was not actually correct and therefore it was not a true negative. In Option 2, the test actually gave a positive outcome (Joe was speeding, it said) and so it cannot be a true negative. In Option 4, the test said that Tony did not have strep, but the test’s result was incorrect.
That leaves only Option 3. The test said that Anna did not know the material. In actuality, she did not know the material as she had not learned it. Therefore, the test correctly gave a negative answer. It is a true negative outcome.