Science
30 October 2015 vol 350, issue 6260, pages 481-596
http://www.sciencemag.org/current.dtl

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Review
The realities of risk-cost-benefit analysis
Baruch Fischhoff
BACKGROUND
Synthetic biology, nanotechnology, geoengineering, and other innovative technologies share a property: Their effects must often be inferred long before they are experienced. If those inferences are sound, then informed decisions are possible. If not, then decision-makers may incur risks and costs far greater than any expected benefits. Risk, cost, and benefit analysis can offer transparent ways to assemble and integrate relevant evidence to support complex decision-making All forms of analysis have the same logic: Decompose complex systems into manageable components and then calculate how they might perform together. All require scientific judgment to bound the set of components and assess the limits to those bounds. All require ethical judgment to determine which outcomes to predict and to extract the policy implications of the results. The usefulness of any analysis depends on how well its underlying assumptions and their implications are understood by those hoping to use its results. The present review uses historical examples to illustrate the roles of judgment in analyses that address four basic questions: (i) How large are the risks from a single technology?(ii) Which risks merit the greatest attention? (iii) Which technology produces the least risk per unit of benefit? (iv) Are a technology’s expected benefits acceptable, given its risks and other expected costs?
ADVANCES
Analyses are always incomplete. They neglect concerns that are hard to quantify. They define terms in ways that serve some interests more than others. They consider some sources of uncertainty but not others. Advances in the science of analysis have often occurred after critics unhappy with the results of an analysis challenged the legitimacy of its assumptions. Awareness of the role of judgment in analysis has grown over time, in parallel with improvements in the sophistication of analytical calculations. Progress has been made in some areas, but more is needed, to include developing better ways to model human behavior, elicit expert judgments, articulate decision-makers’ preferences, characterize the robustness of conclusions, and communicate with decision-makers. The practice of analysis draws on the sciences of public participation and science communication, both shaped by the challenges faced in securing a fair hearing for science in issues where it plays a central role.
OUTLOOK
The pace of advances will depend on the degree of collaboration among the sciences relevant to these problems, including not only the sciences underlying the technology in question but social, behavioral, and economic science as well. How well the science of analysis aids its practice will depend on how well analysts collaborate with decision-makers so as to produce the estimates that decision-makers need and ensure that analytical results are properly understood. Over time, those interactions will help decision-makers understand the capabilities and limitations of analysis while helping analysts become trusted allies, dedicated to producing relevant, properly qualified estimates of cost, risk, and benefit.