Summary of the four RCTs with blinding assessment
| Study | Intervention and comparison (n) | Types of RCT | Who guessed? | Proportion of correctly guessed | Kappa statistics |
| Hall and Dunlap7 | Chlorpromazine (87): 750 mg maximum Placebo (88) | Parallel | Psychiatrists and psychologists | Psychiatrists: 70.3% Psychologists: 74.3% (only ‘unchanged’ cases) | Psychiatrists: 0.37 Psychologists: 0.47 (only ‘unchanged’ cases) |
| Simpson et al 6 | Haloperidol 6 mg (8) Haloperidol 30 mg (8) Placebo (8) | Parallel | Doctors and nurses | Doctors: 91% Nurses: 89.5% | Not calculable |
| Engelhardt et al 5 | Chlorpromazine (103): mean 180 mg (range 50–800 mg) Promazine (109): mean 180 mg (range 50–800 mg) Placebo (99) | Parallel | Doctors | 76.8% (combined active drugs) | 0.45 (combined active drugs) |
| George et al 8 | Dihydrexidine (20): 20 mg Placebo (20) | Crossover | Participants and raters | Participants: 86% Raters: 80% | Not calculable |
RCT, randomised controlled trial.