Sidebar: Understanding screening tests: sensitivity versus specificity, false positives and false negatives, and probabilities of having a disease

There are important differences in the meanings and consequences of the words used to describe the accuracy of a diagnostic or screening test. A test that can correctly identify a disease among a group of people with a disease (sensitivity), is different from a test that can correctly identify those without a disease among a group of healthy people (specificity). No one wants a screening test (