How to GRADE the evidence: Imprecision

This lesson is the sixth in the series of online learning materials designed to help guideline developers and authors of systematic reviews learn how to use the GRADE approach to grade the evidence in systematic reviews, to create Summary of Findings Tables and GRADE Evidence Profiles, and move from evidence to making recommendations.

This lesson deals with imprecision and explains how judgements in GRADE approach are made about imprecision and precision. It discusses the question of when the results are precise enough and introduces the concept of Optimal Information Size (OIS). Finally, examples are provided to exercise the judgments on downgrading the evidence based on imprecision.

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After using this resource, you should be able to...
  • know what to consider when judging the precision of an estimate of effect
  • understand the concept of Optimal Information Size
  • make a decision on downgrading the evidence based on imprecision

Assessing imprecision

Author information: 
Sch√ľnemann, Holger; Santesso, Nancy

Prepared by Holger Sch√ľnemann and Nancy Santesso from the Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada. Funding for the development of this lesson was provided by the Cochrane Collaboration through the grant 'Training and Capacity Building for Summary of Findings Tables' and the World Health Organization.