In medical literature the value of diagnostic tests is most of the time appreciated from their statistical properties (sensitivity and specificity) and from the prevalence of a given disease. In this paper we also take into account economic parameters such as the benefits and costs of the potential treatment under consideration and we present a simple and flexible algebraic expression of the informative value of a test. In this way the informative content of a test can be easily evaluated and the quality of an existing test can be compared to that of a theoretically 'perfect' one. Two examples taken from the medical literature illustrate our approach.
Biopsy, Needle Clinical Laboratory Techniques