It is an inferential process that may be used throughout an entire assessment, such as causal assessments using the CADDIS framework ( ). Contrary to some usages, WoE is not a type of assessment. We begin by clarifying terms and the concepts to which they apply.Īn environmental WoE is an inferential process that assembles, evaluates, and integrates evidence to perform a technical inference in an assessment. Much of the confusion and controversy surrounding WoE results from vague and inconsistent terminology used to describe basic concepts. In practice, assessors should apply it flexibly to ensure that each application is fit for purpose. Like the framework and guidelines for ecological risk assessment ( USEPA 1992 USEPA 1998), it is intended to provide a common process and terminology that can be adapted and applied to many different assessment problems and contexts. Environmental Protection Agency (USEPA) assessments. Its major elements have been employed in externally peer‐reviewed U.S. 2007 Suter and Cormier 2011) and health risk assessment ( Rhomberg et al. This framework is new, but it is derived from the diverse WoE approaches in ecological assessment ( Fox 1991 Burton et al. Hence this framework transparently organizes and presents judgments and does not engage in pseudo‐quantification (assigning numbers to qualities) or in ignoring the qualitative aspects of an issue so as to make it quantitative (e.g., limiting assessment of causation to correlations). Finally, the properties of evidence that are weighed such as relevance are not quantitative. In addition, some qualities, particularly causation, have no quantitative metric (Norton et al. For example, some evidence may indicate that a cause and effect are co-located while other evidence indicates that affected organisms are altered in characteristic ways, so the evidence is not commensurable and cannot be quantitatively combined. While quantitative analysis is essential to generating evidence, there is no way to quantitatively combine the heterogeneous evidence that appears in environmental assessments and serves different purposes. WoE to infer qualities employs both qualitative and quantitative methods, and it inevitably requires subjective judgment. However, WoE may also be employed to derive quantities such as benchmark concentrations or half‐lives of chemicals (Suter et al. The framework presented here can be used to integrate multiple pieces of evidence and to infer qualities such as causation, teratogenicity, or impairment. ![]() The approach is potentially applicable to human health and welfare assessments, but ecological assessors have, in general, been more accepting of the formal weighing of multiple types of evidence. The USEPA (2016) has developed and adopted WoE guidelines for ecological assessments. Although the weighing is often done by unstructured narratives or narratives guided by a list of considerations, an explicit weight-of-evidence (WoE) process can increase the defensibility of results ( Weed 2005). Such inferences require weighing the evidence. For example, inferring the cause of an observed biological impairment could involve evidence derived from conventional laboratory tests, ambient media tests, biomarkers, biological surveys, chemical analyses, and models. ![]() ![]() Inferences in environmental assessment often involve multiple and heterogeneous pieces of evidence.
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