Diagnostic testing in the context of high-value care: Incorporating prior probability.

This is the fifth article of a series on fundamental concepts in biostatistics and research. In this article, the author reviews the fundamental concepts in diagnostic testing, prior probability and predictive value, and how they relate to the concept of high-value care. The topics are discussed in common language with a minimum of jargon and mathematics. Emphasis is given to conceptual understanding. A companion article preceding this one focused on sensitivity and specificity.