When are predictions useful? a new method for evaluating epidemic forecasts

We introduce the Weighted Contextual Interval Score (WCIS), a new method for evaluating the performance of short-term interval-form forecasts. The WCIS provides a pragmatic utility-based characterization of probabilistic predictions, developed in response to the challenge of evaluating forecast performances in the turbulent context of the COVID-19 pandemic. Current widely-used scoring techniques generally fall into two groups: those that generate an individually interpretable metric, and those that generate a comparable and aggregable metric. The WCIS harmonizes these attributes, resulting in a normalized score that is nevertheless intuitively representative of the in-situ quality of individual forecasts. This method is expressly intended to enable practitioners and policy-makers who may not have expertise in forecasting but are nevertheless essential partners in epidemic response to use and provide insightful analysis of predictions. In this paper, we detail the methodology of the WCIS and demonstrate its utility in the context of US state-level COVID-19 predictions. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by the National Science Foundation under grant no. 2108526 ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study used ONLY openly available human COVID-19 outcome data that were originally located at: AND I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors