Press Release: Climate Predictions are Better Understood by Adding Numerical Estimates To Verbal Communications, According to Carnegie Mellon Research-Carnegie Mellon News - Carnegie Mellon University

Wednesday, April 30, 2014

Press Release: Climate Predictions are Better Understood by Adding Numerical Estimates To Verbal Communications, According to Carnegie Mellon Research

Contact: Shilo Rea / 412-268-6094 / shilo@cmu.edu

BroomellPITTSBURGH—Scientists describing phenomena such as global warming would be better served by using both numbers and verbal terms to communicate their findings, according to new research published in Nature Climate Change.

Carnegie Mellon University's Stephen Broomell teamed up with researchers in 24 countries to measure how well policymakers and the public understand statements that the Intergovernmental Panel on Climate Change (IPCC) uses to describe scientists' research findings. Broomell, assistant professor of social and decision sciences in the Dietrich College of Humanities and Social Sciences, and the research team found that the public usually interprets verbal terms in a conservative fashion. However, supplementing the verbal phrases with numbers considerably improved communication.

"Supplementing standard language with numeric values clarifies the amount of uncertainty a scientist is dealing with for most individuals around the world," Broomell said. "This is precisely the type of communication strategies required to effectively convey information about climate science as well as many other uncertain global issues."

For the study, 1,000 volunteers in 24 countries and in 17 different languages were asked to provide their interpretations of the intended meaning and possible range of eight sentences from the IPCC report that included various phrases such as "very likely," "likely," "unlikely" and "very unlikely." In the context of the report, each term is meant to correspond to a range of numerical probabilities - "very likely refers to 90 percent or higher probability, and "unlikely" means 33 percent or lower probability.

The results revealed that a small minority of the participants interpreted the probability of these statements as consistent with IPCC guidelines, and the vast majority interpreted  these statements to convey probabilities as being closer to 50 percent than the intended percentages by IPCC authors. The benefits of the dual presentation — words and numbers — were especially large for the most extreme words where it doubled the rate of interpretations consistent with the IPCC guidelines.

The researchers, who were led by David Budescu, the Anne Anastasi Chair in Psychometrics and Quantitative Psychology at Fordham University, recommended that the IPCC use both words and numbers to communicate uncertainty and probability in all its future reports.  The researchers said this alternative communication format is more flexible, it appeals to all — people who prefer numerical presentations and those who favor natural language — and would improve greatly the public's understanding of the IPCC reports' findings.

For more information, visit http://www.fordham.edu/Campus_Resources/eNewsroom/topstories_3177.asp.

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CMU's Stephen Broomell (pictured above) teamed up with researchers in 24 countries to measure how well policymakers and the public understand statements that the Intergovernmental Panel on Climate Change uses to describe scientists' research findings.