A team of Alaska researchers led by ISER’s Tobias Schwoerer has proposed a new methodology to elicit and quantify expert scientific opinion in uncertain environmental applications. The work, which was co-authored with Joseph Little (UAF)  and Gregory Hayward (Alaska Region, US Forest Service), appeared in an article in the Journal of Environmental Management under the title “Quantifying expert opinion with discrete choice models:  Invasive elodea’s influence on Alaska salmonids.”  The new methodology can be used to combine the expert perspectives of many scientists in a way that provides a quantitative measure of which aspects of the problem scientists agree upon and which aspects have less consensus.

Discrete choice modeling is often applied in market research to determine how consumers value various characteristics of a product.  A sample of consumers is asked to make “discrete choices” between products with different combinations of characteristics.  Each consumer faces a small set of choices, but statistical techniques can be used to combine the decisions of many consumers into an understanding of the relative importance of different characteristics across the many consumers.  Similarly, Schwoerer and his team propose asking a large panel of scientists to each predict how a small number of different scenarios will affect an environmental objective.   Those individual predictions are then combined statistically.

This research applied the discrete choice methodology to elicit expert opinion on the impact of elodea, an invasive aquatic plant, on the sustainability of salmonid populations.  A group of 56 experts evaluated various scenarios.  The methodology allowed participation by a wide range of experts, including those from Alaska and from Outside and those with expertise in various aspects of the problem.  Those experts showed strong agreement that the impact of elodea on dissolved oxygen levels was very important in assessing how elodea will affect salmonid population sustainability.  There was less agreement on how changes in prey abundance and predator densities caused by elodea affect salmonid population sustainability.