Assessment of masking to vignette or commissioning brief allocation
| Subset | Correct guess of allocation | Incorrect guess of allocation | Significance* |
| All responses | 222 (62.4%) | 134 (37.6%) | p<0.00001 |
| Received vignette | 104 (57.4%) | 77 (42.6%) | p=0.053 |
| Received commissioning brief | 118 (67.4%) | 57 (32.6%) | p<0.00001 |
*Binomial test, assuming that, if masking were perfect, the correct guess rate would be 0.5, see Statistical methods section.