The Advantages of Predictive Interval Forecasts for Non-Expert Users and the Impact of Visualizations


Correspondence to: Sonia Savelli, Department of Psychology, University of Washington, PO Box 351525, Seattle, WA 98105, USA.



Three experiments demonstrated advantages over conventional deterministic forecasts for participants making temperature estimates and precautionary decisions with predictive interval weather forecasts showing the upper and lower boundaries within which the observed value is expected with a specified probability. Participants using predictive intervals were better able to identify unreliable forecasts, expected a narrower range of outcomes, and were more decisive than were participants using deterministic forecasts. Predictive interval format was also manipulated to determine whether adding visualizations enhanced understanding. Some participants using visualizations misinterpreted predictive intervals as expressions of diurnal fluctuations (deterministic forecasts). Almost no misinterpretations occurred when the predictive interval was expressed in text alone. Moreover, no advantages were found for visualizations over text-only formats, demonstrating that visualizations, especially those investigated in these studies, may not be suitable for expressing this concept. Thus, predictive intervals are both understandable and advantageous to non-expert decision makers, as long as they are carefully expressed. Copyright © 2013 John Wiley & Sons, Ltd.