Table 4 Simulation results for dropping treatment arms based on the second rule (R2) and the absolute bias for such arms in the estimated treatment effect at the time of dropping decision – all priors on pk (k=A,B,C) are non-informative beta(1,1) priors, when decision threshold is set at 0.05
Sample size | True benefit | Posterior mean estimate biases | Average sample sizes | % Early stopping | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
n | dB | dC | pA | pB | pC | A | B | C | B | C |
40 | −0.20 | 0.00 | 0.0446 | 0.0410 | −0.0036 | 34.7688 | 19.0005 | 34.1757 | 83.18 % | 20.90 % |
−0.15 | 0.00 | 0.0407 | 0.0196 | −0.0049 | 35.4230 | 23.9111 | 34.1465 | 65.96 % | 21.12 % | |
−0.10 | 0.00 | 0.0384 | 0.0076 | −0.0045 | 36.0178 | 28.2528 | 33.9857 | 47.31 % | 21.51 % | |
−0.05 | 0.00 | 0.0325 | 0.0004 | −0.0039 | 36.8988 | 31.7086 | 34.2757 | 31.84 % | 20.67 % | |
0.00 | 0.00 | 0.0289 | −0.0046 | −0.0034 | 37.5750 | 34.3312 | 34.2628 | 20.68 % | 20.55 % | |
0.05 | 0.00 | 0.0262 | −0.0053 | −0.0046 | 38.1404 | 35.9159 | 34.2368 | 13.61 % | 21.01 % | |
0.10 | 0.00 | 0.0212 | −0.0068 | −0.0038 | 38.6097 | 37.1804 | 34.2661 | 8.79 % | 20.81 % | |
0.15 | 0.00 | 0.0184 | −0.0079 | −0.0043 | 39.0075 | 38.0515 | 34.3098 | 5.79 | 20.69 % | |
0.20 | 0.00 | 0.0163 | −0.0098 | −0.0051 | 39.2281 | 38.5864 | 34.2477 | 4.01 % | 20.85 % | |
100 | −0.20 | 0.00 | 0.0458 | 0.0362 | −0.0144 | 80.7525 | 22.0750 | 80.0766 | 99.05 % | 26.36 % |
−0.15 | 0.00 | 0.0427 | 0.0103 | −0.0153 | 81.9307 | 34.6011 | 79.9595 | 91.50 % | 26.58 % | |
−0.10 | 0.00 | 0.0418 | −0.0063 | −0.0152 | 83.5055 | 51.2404 | 79.0897 | 71.48 % | 27.30 % | |
−0.05 | 0.00 | 0.0344 | −0.0142 | −0.0153 | 87.6493 | 67.8997 | 80.1142 | 46.17 % | 26.49 % | |
0.00 | 0.00 | 0.0277 | −0.0161 | −0.0157 | 90.8189 | 79.7603 | 79.7672 | 26.62 % | 26.82 % | |
0.05 | 0.00 | 0.0247 | −0.0149 | −0.0154 | 93.1423 | 86.5031 | 79.4970 | 15.96 % | 26.65 % | |
0.10 | 0.00 | 0.0202 | −0.0130 | −0.0157 | 95.3857 | 91.6455 | 78.7749 | 9.26 % | 27.54 % | |
0.15 | 0.00 | 0.0154 | −0.0119 | −0.0155 | 96.8064 | 94.2754 | 79.4074 | 6.15 % | 27.04 % | |
0.20 | 0.00 | 0.0112 | −0.0100 | −0.0147 | 97.8693 | 96.1853 | 80.1669 | 4.03 % | 26.14 % | |