Improving the communication of uncertainty in climate science and intelligence analysis

Public policymakers routinely receive and communicate information characterized by uncertainty. Decisions based on such information can have important consequences, so it is imperative that uncertainties are communicated effectively. Many organizations have developed dictionaries, or lexicons, that contain specific language (e.g., very likely, almost certain) to express uncertainty. But these lexicons vary greatly and only a few have been empirically tested. We have developed evidence-based methods to standardize the language of uncertainty so that it has clear meaning understood by all parties in a given communication. We tested these methods in two policy-relevant domains: climate science and intelligence analysis. In both, evidence-based lexicons were better understood than those now used by the Intergovernmental Panel on Climate Change, the U.S. National Intelligence Council, and the U.K. Defence Intelligence. A well-established behavioral science method for eliciting the terms’ full meaning was especially effective for deriving such lexicons.