From Gambling to Global Catastrophe: Metaphors and Images for Communicating Numerical Risks

• Activity Number: 578
• Type: Invited
• Date/Time: Wednesday, August 7, 2013 : 2:00 PM to 3:50 PM
• Sponsor: IMS
• Author(s): David John Spiegelhalter*+
• Companies: University of Cambridge
• Keywords: risk communication ; probability

Abstract

In Ars Conjectandi, Jakob Bernouilli made the historic connection between the mathematics of gambling, based on calculable 'chances', and real-world personal, judicial, and financial decisions, in which 'probabilities' could be considered as degrees of certainty. This slightly uneasy connection continues to the present day, so that we use games of chance to start teaching probability, which is then merrily applied to drug trials, finance, insurance, election and weather forecasting and other established areas of statistics.

I will argue that, in these messier applications, 'probabilities' do not exist as part of the outside world, but are constructed on the basis of current knowledge, judgment and numerous assumptions. This is very liberating, since it opens up the possibility of using different metaphors for communication, such as betting odds, enumerating possible futures, and the 'chance of being wrong'. I will illustrate these ideas with numerous examples of risk communication, some good but, in order to get some cheap laughs, mainly bad.