21.4  Assessment of study quality and risk of bias

Assessing the quality of public health and health promotion studies, and their resulting risk of bias, may be difficult, partly due to the wide variety of study designs used. Authors need to consider the criteria to be used to assess quality at the planning stage of the review. Appraisal criteria will depend on the type of study included in the review. Authors should be guided by the Cochrane Review Group (CRG) editing their review and the appraisal tools they use. However the following describes tools which may be useful for assessing studies of public health and health promotion interventions.