A distribution-free approach for selecting better treatment through an ethical allocation

ABSTRACT

The present article provides a statistical inference on comparative performances of two treatments in a clinical trial under a two-stage adaptive allocation design. Suppose a fixed number (2m+n, say) of subjects are available for treatment by any of the two competing treatments, say, A and B for a particular ailment. As per the proposed allocation design, $2m$ incoming subjects are randomised equally between A and B at the first stage. Then, at the second stage, the remaining n subjects are exclusively assigned to the treatment which has higher observed median response evaluated in the first stage. Under such an ethical allocation design we decide on the better treatment through an asymptotically distribution-free test procedure. The related asymptotic results are also studied.

KEYWORDS:

• Two-stage adaptive allocation
• complete randomisation rule
• distribution-free test and asymptotic power

Acknowledgments

The author is very grateful to the anonymous referees and editorial board for their constructive comments which help to improve the contents of the paper.

Disclosure statement

No potential conflict of interest was reported by the author.