Table 3

Significance of the four levels of evidence51

Quality levelDefinition
Embedded Image
high
We are very confident that the true effect lies close to that of the estimate of the effect
Embedded Image
moderate
We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Embedded Image
low
Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect
Embedded Image
very low
We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect