When a test is performed to detect a disease, there are four possible outcomes.
If a test indicates that a patient has a disease that the patient does indeed have, this is called a true positive.(1)
However, if the test indicates that a patient has a disease when she does not, it is called a false positive.(1)
If the test indicates the patient is disease-free, and this is indeed the case, it is called a true negative.(1)
Finally, if the test indicates the patient is healthy when in fact the patient has the disease, we call this a false negative.(1)
Click on the image below to view a documentary on false positives and negatives.
On the next page you can learn more about medical tests and watch our documentary on sensitivity and specificity.