Medical measurements and uncertainties

Measurements in the medical field are peculiar in at least two ways: they deal with a terribly complex object-the patient-and are performed and managed by another terribly complex instrument-the physician. However, they are measurements and, like all measurements, they have their own uncertainty, which can affect any decision regarding the invaluable - object to be measured-the patient. This article, without any claim to be exhaustive, discusses how the uncertainty of a complex clinical measurement can be estimated, how the physician-based instrument affects it, and how it can affect the final diagnosis.