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:Whereas Lorden used crude upper bounds for the Type I error probability that are too conservative for practical applications, Bartroff and Lai (2008) overcome this difficulty by developing numerical methods to compute the Type I error probability and also extended the three-stage test to multiparameter and multi-armed settings, thus greatly broadening the scope of these efficient adaptive designs. A review of their method is given in Section 2.1. In Section 4 we prove the asymptotic optimality of these adaptive tests in the multiparameter case, extending Lorden’s (1983) result for the special case d = 1.
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