Confusion, Consensus, Certainty

Longtime user of Palisade’s Monte Carlo software and other decision analysis tools, Willy Aspinall uses these tools to beat back some heavy-duty varieties of uncertainty.  How long will it be before a volcano actually blows its top as opposed to gurgles over its rim?  What factors should transportation officials focus on to reduce the likelihood of airline disasters?  What are the acceptable limits of air pollution?  What exactly will the climate be like for our grandchildren?
Aspinall is often called upon to provide expert testimony on these kinds of life-and-death questions, and he has recently called attention to one of the problems with expert testimony, including his own:  In which expert should you place your confidence? In an opinion piece in this January’s Nature–a magazine that is an icon of scientific validity–Aspinall describes the benefits of using a method called "expert elicitation" to balance the opinions of a group of experts.  The method, developed by Roger Cooke of Resources for the Future, attempts to quantify and then pool the uncertainties to arrive at what Cooke calls a "rational consensus."

When experts disagree, Cooke has pointed out, any attempt to impose agreement will "promote confusion between consensus and certainty."  In order to get around this problem, Aspinall points out in his article, the goal of risk analysis should be to "quantify uncertainty, not to remove it from the decision process."  His ongoing  risk assessment of volcanic activity on the island of Monserrat in the West Indies is the longest running application of Cooke’s "expert elicitation" method.  For details about how the elicitation and the pooling of opinion works, I recommend taking a look at the January 2010 issue of Nature.  

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