Risk Perception

How many words equal a number?

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Science  04 Jul 2014:
Vol. 345, Issue 6192, pp. 43
DOI: 10.1126/science.345.6192.43-b

The probability that an event will occur can be expressed in words (“very unlikely”) or in numbers (“<10%”). Budescu et al. show that to communicate clearly to a lay audience, it is better to use words and numbers together than words alone. They asked 10,000 adults across 25 countries to give their numerical interpretation of probability terms (very unlikely, unlikely, likely, or very likely) used in Intergovernmental Panel on Climate Change (IPCC) statements. With only words, people interpreted unlikely events to be more likely than the IPCC intended, and vice versa. When the experimenters used both words and numerical ranges, however, the respondents estimated probabilities more accurately.

Nat. Clim. Change 4, 508 (2014).

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