Core GRADE 2: choosing the target of certainty rating and assessing imprecision.

This second article in a seven part series presents the Core GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach to deciding on the target of the certainty rating, and decisions about rating down certainty of evidence due to imprecision. Core GRADE users assess if the true underlying treatment effect is important or not in relation to the minimal important difference (MID) or, alternatively, if a true underlying treatment effect exists. The location of the point estimate of effect in relation to the chosen threshold determines the target. For instance, using the MID thresholds, a point estimate greater than the MID suggests an important effect and less than the MID, an unimportant or little to no effect. Users then rate down for imprecision if the 95% confidence interval crosses the MID for benefit or harm.