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:…found similar results when their outcome was alcohol and marijuana use during midadolescence, regardless of whether popularity measures were based on preference, as in the present study ~Allen et al., 2005!, or based on reputation ~Prinstein & Cillessen, 2003; Prinstein, Meade, & Cohen, 2003!.
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