Table 2 Quality synthesis
Level | Rating | Description |
|---|---|---|
Strong | +++ (−−−) | Consistent positive (negative) ratings derived from multiple studies of good quality, or in one study of excellent quality |
Moderate | ++ (−−) | Consistent positive (negative) ratings in multiple studies of fair quality, or in one study of good quality |
Limited | + (−) | Positive (negative) rating in one study of fair quality |
Conflicting | +/− | Conflicting results |
Unknown | ? | Only studies of poor quality |