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:This central role of experimentation has generated an ongoing interest in the definition of adequate experimental protocols and the use of inferential procedures for comparing two or more algorithms, either on single or multiple problem instances [2, 46, 34, 18, 37, 58, 22, 59, 9, 11, 5, 6, 30, 29, 24, 23, 16, 39, 33, 8].
Category: