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:Depression Assessment The Montgomery-Åsberg Depression Rating Scale (MADRS) [13] is increasingly employed in clinical research since results from earlier studies had suggested that the scale could be superior to the traditional HAMD17 with respect to sensitivity to change [13,14,15] and other psychometric properties [16].
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