Categories of supporting comments for judgments of bias associated with the generation of randomisation sequence | Total, N (%) | High, N (%) | Unclear, N (%) | Low, N (%) |
---|---|---|---|---|
Random number table (low risk†) | 883 (8.7) | 11 (1.2) | 31 (3.5) | 841 (95.2) |
Random number table | 883 (100.0) | 11 (1.2) | 31 (3.5) | 841 (95.2) |
Randomisation via computer/software/internet (low risk†) | 2850 (28.2) | 2 (0.1) | 36 (1.3) | 2812 (98.7) |
Computer/software generated | 2459 (86.3) | 0 (0.0) | 17 (0.7) | 2442 (99.3) |
IVRS* | 60 (2.1) | 0 (0.0) | 7 (11.7) | 53 (88.3) |
Minimisation | 103 (3.6) | 2 (1.9) | 8 (7.8) | 93 (90.3) |
Random number generator (without mention of computer) | 98 (3.4) | 0 (0.0) | 0 (0.0) | 98 (100.0) |
Web based | 130 (4.6) | 0 (0.0) | 4 (3.1) | 126 (96.9) |
Mechanical method of randomisation (low risk†) | 359 (3.6) | 7 (1.9) | 37 (10.3) | 315 (87.7) |
Coin tossing | 85 (23.7) | 0 (0.0) | 1 (1.2) | 84 (98.8) |
Drawing of lots | 201 (56.0) | 4 (2.0) | 12 (6.0) | 185 (92.0) |
Shuffling cards or envelopes | 60 (16.7) | 3 (5.0) | 24 (40.0) | 33 (55.0) |
Throwing dice | 13 (3.6) | 0 (0.0) | 0 (0.0) | 13 (100.0) |
Incomplete or inappropriate randomisation (high risk†) | 305 (3.0) | 264 (86.6) | 32 (10.5) | 9 (3.0) |
Quasi random | 238 (78.0) | 209 (87.8) | 22 (9.2) | 7 (2.9) |
Incomplete, erroneous randomisation | 41 (13.4) | 34 (82.9) | 7 (17.1) | 0 (0.0) |
Judgment, preference, availability | 26 (8.5) | 21 (80.8) | 3 (11.5) | 2 (7.7) |
Method of randomisation was not described (unclear risk†) | 5706 (56.5) | 81 (1.4) | 4651 (81.5) | 974 (17.1) |
Not described | 4586 (80.4) | 69 (1.5) | 4272 (93.2) | 245 (5.3) |
Block randomisation/stratification | 679 (11.9) | 2 (0.3) | 219 (32.3) | 458 (67.5) |
Envelopes | 247 (4.3) | 3 (1.2) | 117 (47.4) | 127 (51.4) |
Central randomisation (statistics department, pharmacy, third party) | 124 (2.2) | 1 (0.8) | 0 (0.0) | 123 (99.2) |
Baseline imbalance between groups | 41 (0.7) | 6 (14.6) | 35 (85.4) | 0 (0.0) |
Baseline balance between groups | 29 (0.5) | 0 (0.0) | 8 (27.6) | 21 (72.4) |
Total, N (%) | 10103 (100.0) | 365 (3.6) | 4787 (47.4) | 4951 (49.0) |