Elicitation Live!

Dr Matthew William
Aston University

Date: 8th March 2011 (Tuesday)
Time: 14:00 - 15:00
Venue: MB504

When constructing and using environmental models, it is typical that many of the inputs to the models will not be known perfectly. In some cases, it will be possible to make observations, or occasionally physics-based uncertainty propagation, to ascertain the uncertainty on these inputs. However, such observations are often either not available or even possible, and another approach to characterising the uncertainty on the inputs must be sought. Even when observations are available, if the analysis is being carried out within a Bayesian framework then prior distributions will have to be specified.

One option for gathering or at least estimating this information is to employ expert elicitation. Expert elicitation is well studied within statistics and psychology and involves the assessment of the beliefs of a group of experts about an uncertain quantity, (for example an input / parameter within a model), typically in terms of obtaining some mathematical form that can be used in a statistical analysis, i.e. a probability distribution.

In this talk I present ‘The Elicitator’ – a Web-based tool for expert elicitation. I provide a technical discussion on the design choices adopted including the Model-View-Controller framework, jStat – an advanced statistical library for JavaScript and the R code (based on SHELF) for fitting and pooling probability distributions. I will finish the talk with a demonstration of The Elicitator, where we will attempt to perform a live elicitation.