Authors will comment on the quality of the body of evidence as ‘High’, ‘Moderate’, ‘Low’, or ‘Very Low’. This is a matter of judgement, but the judgement process operates within a particular structure and is described in Chapter 12 (Section 12.2). As an example, the quality would be ‘High’ if the summary is of several randomized trials with low risk of bias, but the rating of quality becomes lower if there are concerns about design or implementation, imprecision, inconsistency, indirectness, or reporting bias. Authors should use the specific evidence grading system developed by the GRADE collaboration (GRADE Working Group 2004), which is described in detail in Chapter 12 (Section 12.2). Judgements other than of ‘High’ quality should be made transparent using footnotes or the Comments column in the ‘Summary of findings’ table (see ).