| 1. Were the aims/objectives of the study clear? |
27 |
| 2. Was the study design appropriate for the stated aim(s)? |
27 |
| 3. Was the sample size justified? |
24 |
| 4. Was the target/reference population clearly defined? (Is it clear who the research was about?) |
26 |
| 5. Was the sample frame taken from an appropriate population base so that it closely represented the target/reference population under investigation? |
22 |
| 6. Was the selection process likely to select subjects/participants that were representative of the target/reference population under investigation? |
2 |
| 7. Were measures undertaken to address and categorise non-responders? |
1 |
| 8. Were the risk factor and outcome variables measured appropriate to the aims of the study? |
27 |
| 9. Were the risk factor and outcome variables measured correctly using instruments/measurements that had been trialled, piloted or published previously? |
17 |
| 10. Is it clear what was used to determined statistical significance and/or precision estimates? (e.g. p-values, confidence intervals) |
24 |
| 11. Were the methods (including statistical methods) sufficiently described to enable them to be repeated? |
24 |
| 12. Were the basic data adequately described? |
27 |
| 13. Does the response rate raise concerns about non-response bias? |
7 |
| 14. If appropriate, was information about non-responders described? |
1 |
| 15. Were the results internally consistent? |
24 |
| 16. Were the results presented for all the analyses described in the methods? |
27 |
| 17. Were the authors' discussions and conclusions justified by the results? |
27 |
| 18. Were the limitations of the study discussed? |
24 |
| 19. Were there any funding sources or conflicts of interest that may affect the authors’ interpretation of the results? |
20 |
| 20. Was ethical approval or consent of participants attained? |
27 |
