Misclassification of reported caffeinated cups a day compared with caffeinated coffee unit standardised cups a day across subgroups
| Characteristic of participant | Base (unweighted) | Proportion (%) of participants with misclassification of coffee consumption using coffee unit measure | Instant coffee as % of all coffee | ||||
| None | 1 cup under | ≥2 cups under | 1 cup over | ≥2 cups over | |||
| Total | 1623 | 73.4 | 17.1 | 4.7 | 4.3 | 0.5 | 72 |
| Male | 667 | 69.1 | 18.4 | 7.2 | 4.7 | 0.6 | 69 |
| Female | 956 | 77.6 | 15.9 | 2.2 | 3.9 | 0.4 | 67 |
| Age 18–34 years | 323 | 71.0 | 18.6 | 4.1 | 5.2 | 1.1 | 68 |
| Age 35–54 years | 613 | 68.5 | 19.6 | 6.5 | 5.1 | 0.3 | 64 |
| Age≥55 years | 687 | 79.1 | 14.0 | 3.2 | 3.1 | 0.4 | 71 |
| Income≤£17 500* (T1) | 405 | 78.5 | 12.2 | 3.5 | 5.5 | 0.2 | 79 |
| Income>£17 500 to ≤£32 383* (T2) | 414 | 74.1 | 16.3 | 3.1 | 5.4 | 1.0 | 71 |
| Income>£32 383* (T3) | 598 | 68.1 | 22.9 | 6.1 | 2.9 | 0.0 | 56 |
| Age 18–34 years and income T1 | 88 | 71.0 | 14.7 | 2.7 | 11.3 | 0.4 | 77 |
| Age 18–34 years and income T2 | 92 | 68.6 | 16.2 | 5.7 | 6.1 | 3.4 | 77 |
| Age 18–34 years and income T3 | 119 | 73.2 | 23.3 | 3.2 | 0.3 | 0.0 | 57 |
| Age 35–54 years and income T1 | 119 | 69.7 | 14.7 | 9.2 | 6.5 | 0.0 | 75 |
| Age 35–54 years and income T2 | 167 | 73.5 | 17.1 | 1.9 | 7.1 | 0.3 | 70 |
| Age 35–54 years and income T3 | 267 | 62.9 | 25.7 | 7.8 | 3.5 | 0.0 | 57 |
| Age≥55 years and income T1 | 198 | 85.8 | 10.1 | 1.4 | 2.7 | 0.2 | 81 |
| Age≥55 years and income T2 | 155 | 79.4 | 15.3 | 2.6 | 2.7 | 0.0 | 70 |
| Age≥55 years and income T3 | 212 | 72.0 | 18.6 | 5.7 | 3.7 | 0.0 | 56 |
*Income tertile data only available for 1335 of 1623 caffeinated coffee drinking participants; upper income tertile for years 7 and 8 of the survey was >£32 216.