In order to accurately place patients into the categories on the last slide, a study should have several characteristics:

A gold standard to define the condition is needed. This may be a diagnostic test, however if a PT diagnosis is to lead to treatment, a treatment outcome may be the best gold standard.

The test must be defined well and applied consistently. Good definitions of a positive test and a negative test must be specified.

The subjects in the study should be similar to those encountered in practice. All subjects should receive both the test and the gold standard.