Risk of bias

Considerations when selecting Risk of Bias method


A decision about which Risk of Bias tool to use for your review should be made at protocol stage and can be re-considered when updating your review.

Start by reading the information on Risk of Bias 2 (RoB 2) available from Cochrane Methods.

Key points:

  • Protocols: choose your Risk of Bias method before drafting your protocol. Changing your method after protocol publication is discouraged.
    • RoB 2 is recommended as the preferred tool for assessing randomised controlled trials in new intervention protocols as per the Handbook.
    • RoB 1 may still be used (see v5.2 or v5.1 of the Handbook).
  • Reviews: implement the Risk of Bias method specified in your protocol.
  • Updates: you can decide whether to switch to RoB 2 at the point of update.
    • There is no expectation that updates of intervention reviews will adopt RoB 2.
    • If you switch to RoB 2 from RoB 1 at the point of update, all risk of bias data from the previous version will be lost when RoB 2 is enabled. You can download or make a copy of your Risk of Bias data before you enable RoB 2 

Covidence is not currently set up to make RoB 2 assessments. You can use Covidence for screening data extraction and import these data into RevMan before importing your RoB 2 data.

Once you have chosen the Risk of Bias method you can implement this in your review or update. See Enable Risk of Bias 2 or Risk of Bias 1.