Continued Development of Methods for Characterizing and Ranking Health, Safety and Environmental Risks

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Risk ranking has become a popular way for citizens to provide advice to environmental decision makers. If such advice is to reflect citizens' informed judgment, methods must be found to provide participants with both an adequate understanding of the underlying science, and with procedural assistance that helps them to address systematically the complexities of the problem. Under this grant, an interdisciplinary team is developing and demonstrating such methods.Risk ranking requires both risk analysis and value-based judgments. In the Carnegie Mellon method, experts create "risk summary sheets," which describe each hazard in clear simple language, and in multi-attribute terms. Then, representative groups of lay people, akin to citizen juries, rank the risks using two converging methods. The first is a "holistic" ranking procedure -- after examining the risk summary sheets, participants are guided through a structured procedure for making overall judgments of relative risk. The second method is a simplified "multi-attribute utility" (MAU) ranking procedure, in which participants assign relative weights to each of the risk attributes described in the summary sheets, allowing implicit ranks to be inferred. Groups then use their initial holistic ranking, and the results of the MAU procedure, in order deliberate and construct a final ranking. The procedure uses a combination of group and individual methods. The former attempt to exploit the multiple perspectives and mutual clarification possible with group interaction. The latter are designed to ensure that individuals continue to express (and reflect on) their personal views. Although the basic approach has been built upon theoretical and empirical results from behavioral social science, making it work in a realistic setting has required a substantial amount of experimentation. To that end, the CMU group has created an elaborate experimental testbed involving 22 health and safety risks in the fictional Centerville Middle School.The current grant is supporting refinement and evaluation of the method using the school test bed. It is also supporting the extension of the method beyond risks to human health and safety to include ecological and other environmental risks with the ultimate goal of developing ways to combine health, safety and environmental risks in a single ranking process.