Statistical efficiency in multiple-to-one comparison trials with optimal allocation ratio

This paper discusses multiple-to-one comparison trials testing a multivalent vaccine product against multiple comparators with respect to immunologic responses. An optimal subject allocation ratio between the multivalent vaccine group and any of the comparators is introduced. This optimal ratio leads to higher statistical efficiency in terms of savings in sample size compared to equal allocation or any other allocation ratios. Several trial design scenarios are considered including assumptions of equal standardized effect size, unequal variance, and unequal standardized effect sizes of the multivalent vaccines versus the multiple comparators.