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Box 10.5.a: The Cochrane Bias Methods Group.

The Bias Methods Group (BMG), previously the Reporting Bias Methods Group, was formally registered as a Methods Group in 2000. The BMG addresses a range of different forms of bias, such as publication bias, language bias, selective outcome reporting bias and biases arising from study design and conduct. A major initiative of the group, in collaboration with the Statistical Methods Group, was the development of the new guidance for assessing risk of bias of included studies in Cochrane reviews.


Activities of BMG members include:

  • undertaking empirical research to examine whether, and in which circumstances, various biases may have a substantial impact on systematic reviews, including the preparation of Cochrane Methodology reviews;

  • undertaking methodological research on how to identify and address potential biases in systematic reviews and meta-analyses;

  • helping to complete and co-ordinate Methods systematic reviews pertinent to the Group’s remit;

  • providing advice to Cochrane entities; and

  • offering training to both Cochrane and non-Cochrane systematic reviewers via formal and informal opportunities.


The BMG membership emailing list is used as a forum for discussion and dissemination of information. Cochrane newsletters and email distribution lists, such as the Cochrane Methods Group newsletter, Cochrane News and CCInfo, are also used for dissemination of group activities. 


Funding: The BMG receives infrastructure funding as part of a commitment by the Canadian Institutes of Health Research (CIHR) and the Canadian Agency for Drugs and Technologies in Health (CADTH) to fund Canadian-based Cochrane entities. This supports dissemination activities, web hosting, travel, training, workshops and a full time Co-ordinator position.


Web site:\bmg