Table 2.
Conditional allocation probability for randomization designs with MTI restriction (For two-arm equal-allocation trials with MTI = 3)
| Randomization Design | Current Imbalance d = nA-nB | |||||||
|---|---|---|---|---|---|---|---|---|
| −3 | −2 | −1 | 0 | 1 | 2 | 3 | ||
| Big Stick Design | 1 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0 | |
| Biased Coin Design with Imbalance Tolerance (pbc = 0.75) | 1 | 0.75 | 0.75 | 0.5 | 0.25 | 0.25 | 0 | |
| Ehrenfest Urn Design | 1 | 0.8333 | 0.6667 | 0.5 | 0.3333 | 0.1667 | 0 | |
| Block Urn Design | 1 | 0.75 | 0.6 | 0.5 | 0.4 | 0.25 | 0 | |
| Asymptotic Maximal Procedure | 1 | 0.7071 | 0.5858 | 0.5 | 0.4142 | 0.2929 | 0 | |
| Permuted Block Design (block size b = 6) | 1st assignment in the block | 0.5 | ||||||
| 2nd assignment in the block | 0.6 | 0.4 | ||||||
| 3rd assignment in the block | 0.75 | 0.5 | 0.25 | |||||
| 4th assignment in the block | 1 | 0.6667 | 0.3333 | 0 | ||||
| 5th assignment in the block | 1 | 0.5 | 0 | |||||
| 6th assignment in the block | 1 | 0 | ||||||
pA: conditional allocation probability assigning the subject to arm A. An assignment is deterministic if pA = 0 or pA = 1.