Certainty of evidence Size of effect Size of effect Size of effect Size of effect
None / minor / not clinically meaningful (0% to 39% relative change)
Small (40% to 60% relative change)
Medium (61% to 80% relative change) Large (81%+ relative change)
High X does not reduce / increase outcome X reduces / increases outcome slightly X reduces / increases outcome X results in a large reduction / increase in outcome
Moderate X probably does not reduce / increase outcome X probably reduces / increases outcome slightly X probably reduces / increases outcome X probably results in a large reduction / increase in outcome
Low X may not reduce / increase outcome X may reduce / increase outcome slightly X may reduce / increase outcome X may result in a large reduction / increase in outcome
Very low It is unclear whether [intervention] has any impact because the certainty of the evidence is very low It is unclear whether [intervention] has any impact because the certainty of the evidence is very low It is unclear whether [intervention] has any impact because the certainty of the evidence is very low It is unclear whether [intervention] has any impact because the certainty of the evidence is very low