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:On the other hand, whereas the benchmark optimal adaptive test needs to assume a specified alternative, these adaptive two-stage tests and the adaptive tests of Bartroff and Lai (2008) do not require such assumptions as they consider the estimated alternative at the end of the first stage.
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