Diagnostic accuracy and ROC curves

the 2x2 diagnostic table; sensitivity, specificity, PPV, NPV and likelihood ratios, each with the clinical question it answers; why PPV depends on prevalence and sensitivity does not; the ROC curve and what a point on it represents; AUC and its interpretation; choosing a cut-off with the Youden index, and why the best cut-off depends on the cost of each error; the SPSS ROC path; comparing two tests; how to report diagnostic accuracy.