The effects of wording on the understanding and use of uncertainty information in a threshold forecasting decision

Many believe that information about small chances of severe weather would be useful to the general public for precautionary action. What is the best way to explain this kind of information to a non‐expert audience? The studies reported here investigated effects of framing (negative vs. positive), format (frequency vs. probability), likelihood (low vs. high) and compatibility (task‐match) on interpretation of verbal expressions of forecast uncertainty and on subsequent forecasting decisions. The crucial factor was the match between the verbal expression and the overall task goal. Errors increased when there was a mismatch between the expression (e.g. winds less than 20 knots) and the task (e.g. post an advisory when winds will exceed 20 knots). However, framing and format had little impact. We conclude that consideration of user expectations arising from the overall task goal is crucial in explaining uncertainty information to a naïve audience. Global expectations overpower other potential effects.