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:Insulin sensitivity was estimated by the insulin sensitivity index (SI) [6]; beta cell function was assessed as an index of the corrected insulinogenic response (CIR) [7] and disposition index (DI=CIR×SI) to adjust insulin secretion for SI.
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