Table 1. Grade the overall certainty of evidence (2).

Grade	Quality level	Definition
A	High	We are confident that the actual impacts closely match the estimated effects
B	Moderate	The true impacts are likely to be similar to the estimates, but there is a chance that they are significantly different
C	Low	The actual impacts may differ significantly from the estimated effects
D	Very low	The estimates are quite uncertain and frequently will be wildly inaccurate