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. Author manuscript; available in PMC: 2014 Aug 1.
Published in final edited form as: J Clin Epidemiol. 2013 Aug;66(8 0):S130–S137. doi: 10.1016/j.jclinepi.2013.02.015

Table 5.

Comparing the design with adaptive randomization to a trial with fixed randomization via power, mean sample size, and the proportion of patients randomized to the therapy with the highest response rate. The same early stopping rules are used in both. All values based upon 1,000 simulations per scenario.

Scenario Adaptive Randomization Fixed Randomization
Power Mean N % to Best Power Mean N % to Best
Null
0.50 – 0.50 – 0.50
0.031 507 N/A 0.029 499 N/A
One Good
0.50 – 0.50 – 0.65
0.90 483 48 0.88 497 33

Two Good
0.50 – 0.65 – 0.65
0.76 679 84 0.86 687 67
One Middle One Good
0.50 – 0.575 – 0.65
0.68 586 47 0.69 599 33

All Bad
0.25 – 0.25 – 0.25
0.044 524 N/A 0.030 509 N/A
All Really Bad
0.10 – 0.10 – 0.10
0.006 400 N/A 0.028 400 N/A

% to Best = Average proportion of patients randomized to the most effective therapy.

Power = probability of identifying a treatment as best or worst at the 0.975 level.