Exact two-sample permutation tests based on the randomized play-the-winner rule

In comparing two treatments in a clinical trial, the randomized play-the-winner rule tends to assign more study subjects to the better treatment. It is applicable when patients have delayed responses to treatments. It is not deterministic and is less vulnerable to experimental bias than other adaptive designs. In this paper, an efficient algorithm is provided to construct exact permutation tests for testing the equality of the two treatments with the randomized play-the-winner rule. The test procedure is illustrated with a real-life example. The example shows that the design used in the trial should not be ignored in the analysis.