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:The Delphi method is an iterative, anonymous, data-driven survey method that facilitates expert-group consensus building.(22) The four defining characteristics of the Delphi method were upheld throughout the process: anonymity, iteration, controlled feedback, and statistical group response.
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