How do laypeople evaluate the degree of certainty in a weather report? A case study of the use of the Web service yr.no

Abstract

Many people depend on and use weather forecasts to plan their schedules. In so doing, ordinary people with no expertise in meteorology are frequently called upon to interpret uncertainty with respect to weather forecasts. With this in mind, this study addresses two main questions: 1) How do laypeople interpret online weather reports with respect to their degree of certainty and how is previous knowledge drawn upon in this interpretation? and 2) Howdo laypeople integrate information in weather reports to determine their degree of certainty? This qualitative study is based on semistructured interviewswith 21Norwegians. The results show the following: (a) only a portion of uncertainty informationwas used, (b) symbolswere sometimes ascribed different meanings than intended, and (c) interpretations were affected by local experiences with wind direction and forecast quality. The informants’ prior knowledge was found to prevail in the event of a conflict with forecast information, and an expected range of uncertainty was often inferred into single-valued forecasts. Additionally, (d) interpretations were affected by the integration of information used to predict the time and location of precipitation. Informants typically interpreted the degree of certainty differently (more or less uncertain) than was intended. Clearer presentation of uncertainty information, a clear intent of all nuances in information, a thorough use of multimodal information, and consideration of users’ needs can help improve communication of forecast uncertainty. The diversity of user approaches makes forecast uncertainty more difficult to communicate and provides possible explanations for why communicating uncertainty is challenging.