Participant responses to ‘What is your best guess as to the percent chance that John actually had COVID-19 at the time of his test, given his test result?’, by test result and message viewed
| Combination of test result and message viewed | N answering 48%–52% (percentage, 95% CI52) | N answering 0% (‘John definitely did not have COVID-19’) (percentage, 95% CI52) | N answering 100% (‘John definitely did have COVID-19’) (percentage, 95% CI52) |
| Positive test | |||
| Control | 25/156 16.0% (11.0% to 22.6%) | 0/156 0.0% (0% to 2.9%) | 24/156 15.4% (10.5% to 21.9%) |
| USA | 37/165 22.4% (16.7% to 29.4%) | 1/165 0.6% (0% to 3.7%) | 26/165 15.8% (10.9% to 22.1%) |
| New Zealand | 30/186 16.1% (11.5% to 22.1%) | 0/186 0.0% (0% to 2.4%) | 12/186 6.5% (3.6% to 11.0%) |
| UK | 39/165 23.6% (17.8% to 30.7%) | 1/165 0.6% (0% to 3.7%) | 40/165 24.2% (18.3% to 31.3%) |
| Experimental | 57/200 28.5% (22.7% to 35.1%) | 2/200 1.0% (0% to 3.8%) | 28/200 14.0% (9.8% to 19.5%) |
| Negative test | |||
| Control | 59/200 29.5% (23.6% to 36.2%) | 15/200 7.5% (4.5% to 12.1%) | 3/200 1.5% (0.3% to 4.5%) |
| USA | 61/177 34.5% (27.9% to 41.7%) | 14/177 7.9% (4.7% to 12.9%) | 1/177 0.6% (0% to 3.5%) |
| New Zealand | 36/159 22.6% (16.8% to 29.8%) | 7/159 4.4% (2.0% to 9.0%) | 1/159 0.6% (0% to 3.8%) |
| UK | 58/178 32.6% (26.1% to 39.8%) | 27/178 15.2% (10.6% to 21.2%) | 0/178 0% (0% to 2.5%) |
| Experimental | 41/158 25.9% (19.7% to 33.3%) | 11/158 7.0% (3.8% to 12.2%) | 0/158 0% (0% to 2.9%) |