- Published reports of the performance of a diagnostic test typically contain values for sensitivity and specificity, as well as an estimate of the test’s predictive value for the particular study setting. The physician who wishes to use the test in a different practice setting must take into account the effect of any differences between the study population and the practice population on the predictive ability of the test. It is especially critical to assess the impact of any alteration in disease prevalence (Knapp and Miller, 1992).

- The objective of this lecture is to examine the overall accuracy of a test, likelihood of disease given a positive or negative clinical outcome as well as the predictive estimate of clinical tests as well as how these predictive estimates can be changed or revised based on the prevalence.

- Again, the following Website may help you if you are new to the concept of validating diagnostic tests.

http://bmj.com/cgi/content/full/315/7107/540