| High: |
 | High confidence that the evidence reflects the true effect. Further research is very unlikely to change our confidence in the estimate of effect. |
| Moderate: |
 | Moderate confidence that the evidence reflects the true effect. Further research may change our confidence in the estimate of effect and may change the estimate. |
| Low: |
 | Low confidence that the evidence reflects the true effect. Further research is likely to change our confidence in the estimate of effect and is likely to change the estimate. |
| Insufficient: |
 | Evidence either is unavailable or does not permit a conclusion. |
From: Radiotherapy Treatments for Head and Neck Cancer
NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.