Details

The PPV and NPV that are used in the evaluation of the clinical accuracy of a diagnostic test applied to a diseased or nondiseased population can be calculated given the sensitivity and specificity of the test. Sensitivity is the fraction of the diseased population with a positive test, while specificity is the fraction of the nondiseased population with a negative test. If we denote by the sensitivity, the specificity and the prevalence, then:

,

.

Given a diseased and a nondiseased population, the specificity can be defined as a function of sensitivity; therefore, we can plot PPV versus NPV (a parametric plot).

The population data in the snapshots describes a bimodal distribution of serum glucose measurements in nondiabetic and diabetic populations [1].

This Demonstration is based on [2].

References

[1] T.-O. Lim, R. Bakri, Z. Morad and M. A. Hamid, "Bimodality in Blood Glucose Distribution: Is It Universal?," Diabetes Care, 25(12), 2002 pp. 2212–2217. doi:10.2337/diacare.25.12.2212.

[2] A. T. Hatjimihail. "Uncertainty of Measurement and Diagnostic Accuracy Measures," from the Wolfram Demonstrations Project—A Wolfram Web Resource. demonstrations.wolfram.com/UncertaintyOfMeasurementAndDiagnosticAccuracyMeasures.