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Table 2 Allocation ratios, overall power and sample size comparisons for the adding a treatment arm design using optimal allocation when treatments finish recruitment at different times

From: Designs for adding a treatment arm to an ongoing clinical trial

Stage 3 ratio

Stage 2 ratio

n23

Correlation

Overall power

1:0.2

2.015:1:1

100

0.170

0.852

1:0.3

1.932:1:1

93

0.176

0.850

1:0.4

1.856:1:1

85

0.181

0.848

1:0.5

1.791:1:1

78

0.186

0.847

1:0.6

1.730:1:1

71

0.191

0.845

1:0.7

1.678:1:1

64

0.197

0.844

1:0.8

1.632:1:1

58

0.202

0.843

  1. The total sample size of the trial is based on an adding a treatment arm with 1:1:1 allocation design with a marginal power of 90% and an FWER of 2.5%
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