Determing the accuracy of a diagnostic-evaluative test in predicting a dichotomous outcome. For methods to determine a cut-off score for the diagnosis of the outcome, please see ROC Curve Part 2 (http://www.youtube.com/watch?v=WO8Re7YqnP0).
The following resource can be used to determine sample sizes for ROC analysis: Hanley JA, & McNeil BJ. (1982). The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology. 143(1), 29-36.