Principles and framework for assessing the risk of bias for studies included in comparative quantitative environmental systematic reviews
The validity of systematic review conclusions, and of decisions based on them, depends on risk of bias assessments being conducted appropriately. However, a random sample of 50 recently-published quantitative environmental systematic reviews found 64% did not include any risk of bias assessment, whilst nearly all that did omitted key sources of bias. Other limitations included lack of transparency, conflation of quality constructs, and incomplete application of risk of bias assessments to the data synthesis. The core principles require that risk of bias assessments are FOCUSED, EXTENSIVE, APPLIED and TRANSPARENT (FEAT). These principles support risk of bias assessments, appraisal of risk of bias tools, and the development of new tools. The framework follows a Plan-Conduct-Apply-Report approach covering all stages of risk of bias assessment. The scope of this paper is any quantitative environmental systematic reviews including, but not limited to, environmental management, conservation, ecosystem restoration, and analyses of environmental interventions, exposures, impacts and risks.