Abstract
Any decision in clinical practice needs to evaluate both reliability (precision) and validity (accuracy) of a diagnostic test. Without knowledge about the reliability, any judgment would be wrong. In diagnostic accuracy research, it is essential to evaluate the diagnostic added value of a test, since a diagnostic accuracy of a single test might be excellent, however for clinical purposes it can be worthless. Like evaluating discrimination, it would be possible to estimate the diagnostic added value by applying ROC of diagnostic model with and without test results in the model.