Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:For the purposes of this article, we use ROC analysis as a method of examining the performance of a classifier at distinguishing between two discrete states of the world (Fawcett, 2006; Macmillan & Creelman, 2005).
Category: