Risk of Bias 2 (RoB 2) tool

The Risk of Bias 2 (RoB 2) tool is an update to the original risk of bias tool that launched in 2008. The relevant chapter in the Cochrane Handbook for Systematic Reviews of Interventions Chapter 8, titled ‘Assessing risk of bias in a randomized trial’. The Methodological Expectations for Cochrane Intervention Reviews (MECIR) Manual includes standards for assessing risk of bias in included studies; C52-60. Up-to-date information from the developers on RoB 2 is available via the Risk of Bias tools website: www.riskofbias.info.

Key Cochrane resources for using RoB 2 in Cochrane Reviews are: 


An Introduction to Risk of Bias 2

The Introduction to RoB 2 is a one-page leaflet with links to short videos that should be watched at different stages of your review, 1) before you start, 2) when writing your Cochrane Review protocol, 3) managing your RoB 2 assessments, and 4) when writing your full Cochrane Review.

 Risk of Bias 2 Cochrane Review Starter Pack   

The Starter Pack includes all the key resources you'll need, including guidance, training, tools, RoB 2 protocol considerations, RoB 2 considerations for reporting the full review, and support.

    Risk of Bias 2 FAQs   

Frequently Asked Questions from authors and editors.

  Risk of Bias 2 Webinars

 The RoB 2 webinar series covers an introduction of RoB 2, detailed sessions on the five RoB 2 domains, reaching overall RoB judgements, RoB 2 bias in other types of studies (crossover and cluster trials) and editorial considerations.

Editorial checklists for RoB 2

Draft editorial checklists for Cochrane Review Groups for checking RoB 2 reporting in Cochrane protocols and reviews.

November 2021: With the publication of the first Cochrane Review from the RoB 2 Pilot, the Cochrane Editorial Board released a position statement 'Status and expectations of implementation of Risk of Bias 2 in Cochrane intervention reviews' and a 'What you need to know about Risk of Bias 2 in Cochrane' Community post updated the wider community.

August 2020 update: A full update on the implementation of RoB 2 to-date will soon be available on the status and expectations of implementation of Risk of Bias 2 in Cochrane intervention reviews. In the meantime, first draft versions of key resources are now available for authors and CRG editorial teams with Cochrane Reviews using RoB 2 (Introductory leaflet, Starter Pack and FAQs).

November 2019 update: Cochrane Reviews teams can use RoB 2 but there is no mandate to yet. Built-in RoB 2 functionality is only available in RevMan Web (not RevMan 5). Development of guidance, training, tools and support is ongoing. A pilot of RoB 2 is underway with Cochrane Review teams with the official roll-out dependent on the first review publishing. If review teams are interested in using RoB 2 they should contact their Managing Editor, Network Associate Editor and the Cochrane Methods Team.  

Cochrane Scientific Committee recommendation (Full statement, July 2017): When officially released the RoB 2 tool will become mandatory for new reviews. It will not need to be applied retrospectively in updated reviews. As of July 2017, the tool is undergoing some final refinement and implementation within Cochrane is underway. Please await further announcements for the official roll-out. This recommendation has Editor-in-Chief approval.

If you have any questions please contact support@cochrane.org.