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:(3) The maximum diameter of the postoperative cavity was greater than 15 mm [14] for avoiding of partial volume effect when measuring, such as adjacent cerebrospinal fluid, the parenchyma FLAIR high signal intensity surrounding the cavity, as well as vessels, etc.
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