BMJ  2003;327 (27 September), doi:10.1136/bmj.327.7417.0-b

Do you ever mix up sensitivity and specificity?

Sensitivity and specificity are common and seemingly simple conventions—so why are they so hard to grasp? Loong (p 716) tackles this conundrum by offering a visual approach to understanding the sensitivity, specificity, and positive and negative predictive values of tests. Emphasising the importance of applying the right side of the brain, he uses a real clinical example to illustrate the distinctions and relationships between these concepts. Contrary to usual belief, Loong says that high sensitivity, which implies a test is effective at correctly identifying people who have the disease, is not necessarily a good thing. In addition, the positive and negative predictive values of tests are not fixed, but change if the prevalence of disease changes.

The perfect test

Related Article

Understanding sensitivity and specificity with the right side of the brain

Tze-Wey Loong
BMJ 2003 327: 716-719. [Extract] [Full Text] [PDF]