Abstract
Two behavioral experiments tested the use of predictive interval forecasts and verification graphics by nonexpert end users. Most participants were able to use a simple key to understand a predictive interval graphic, showing a bracket to indicate the upper and lower boundary values of the 80% predictive interval for temperature. In the context of a freeze warning task, the predictive interval forecast narrowed user expectations and alerted participants to the possibility of colder temperatures. As a result, participants using predictive intervals took precautionary action more often than did a control group using deterministic forecasts. Moreover, participants easily understood both deterministic and predictive interval verification graphics, based on simple keys, employing them to correctly identify better performing forecast periods. Importantly, participants with the predictive interval were more likely than those with the deterministic forecast to say they would use that forecast type in the future, demonstrating increased trust. Verification graphics also increased trust in both predictive interval and deterministic forecasts when the effects were isolated from familiarity in the second study. These results suggest that forecasts that include an uncertainty estimate might maintain user trust even when the single-value forecast fails to verify, an effect that may be enhanced by explicit verification data.
