next front |1 |2 |3 |4 |5 |review

"The choice of values for test sensitivity, specificity and predictive value and ultimately, the definition of the “positivity criterion” depend on a decision whether it is worse to label a patient diseased when he is not (false positive) or to label him disease-free when he is not (false negative). This tradeoff should take into account the needs of the patient as well as the judgement of the physician" (Knapp and Miller, 1992).


1. When the consequences of missing a case are potentially grave.

2. When a false positive diagnosis may lead to a risky treatment.

-Receiver operating characteristic (ROC) curves are used to compare the performance of two competing diagnostic tests and to determine the appropriate cutoff values of those tests. The technique is used when you have a continuous criterion (predictor or independent) variable which will be used to make a yes or no decision. ROC curves are most often employed in the medical fields. It may be used with any classification procedure. For example, in may be used with two-group discriminant analysis to help determine the appropriate cutoff value of the discriminant score for classifying a individuals (Knapp and Miller, 1992).