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Table 1 Sample Size Calculation

From: Benefits, challenges and obstacles of adaptive clinical trial designs

Randomization Ratio Failure Rate Power
  Placebo Test 80% 85% 90%
1:1 60% 30% 80 (40) 90 (45) 106 (53)
  55% 27% 90 (45) 102 (51) 120 (60)
  50% 25% 110 (55) 126 (63) 148 (74)
  45% 22% 126 (63) 144 (72) 168 (84)
  40% 20% 158 (79) 180 (90) 212 (106)
2:1 60% 30% 93 (62) 105 (70) 123 (82)
  55% 27% 105 (70) 120 (80) 141 (94)
  50% 25% 132 (88) 150 (100) 174 (116)
  45% 22% 150 (100) 171 (114) 201 (134)
  40% 20% 189 (126) 216 (144) 255 (170)
  1. Note: 1. The numbers are the total sample sizes required, while the numbers in the parentheses are the sample sizes required for the test group.
  2. 2. Sample sizes do not adjust for possible dropouts.