Sample size requirements
| Attribute/level | Expected sample size required to estimate parameter by design type | |
| D-Efficient | Bayesian | |
| Psychological intervention | ||
| Home-based with telephone support | 290 | 308 |
| Home-based with face-to-face support | 245 | 251 |
| Group face-to-face in primary or community care | 370 | 362 |
| Group face-to-face in secondary care | 227 | 228 |
| Information provided | ||
| No information | 41 | 41 |
| Printed leaflet | 126 596 | 120 853 |
| Overview from a healthcare professional | 304 | 321 |
| Overview from a healthcare professional plus printed leaflet | 89 | 87 |
| Format of the therapy manual and exercises | ||
| Paper copy plus CD | 39 768 | 39 841 |
| Paper copy plus DVD | 960 | 924 |
| Paper copy plus website | 179 | 190 |
| Paper copy plus smartphone application | 104 | 100 |
| Additional cost to the National Health Service | 2 | 2 |
| Programme start | 25 | 24 |