Frequency of claims of ‘no treatment differences/effects’ in 2001/202 and 2016/207
| Alderson and Chalmers1 | Gates and Ealing2 | Marson-Smith et al (unpublished) | Marson-Smith et al (unpublished) | |
| Reports analysed | Cochrane systematic reviews | RCTs reported in BMJ, JAMA, Lancet and New England Journal of Medicine | Cochrane systematic reviews | Other systematic reviews |
| Years sampled | 2001–2002 | 2016–2017 | 2017 | 2017 |
| Number of reports analysed | 1212 (989+80+143) | 120 | 640 | 218 |
| Number claiming ‘no difference’ or ‘no effect’ | 259 (240+19) | 9 | 36 | 13 |
| Proportion claiming no difference or no effect (%) | 21.3 | 7.5 | 7.8 | 6.0 |
RCT, randomised controlled trial.