Learning as We Go: An Examination of the Statistical Accuracy of COVID19 Daily Death Count Predictions

A recent model developed at the Institute for Health Metrics and Evaluation (IHME) provides forecasts for ventilator use and hospital beds required for the care of COVID19 patients on a state-by-state basis throughout the United States over the period March 2020 through August 2020. In addition, the manuscript and associated website provide projections of deaths per day and total deaths throughout this period for the entire US, as well as for the District of Columbia. Our goal in this report is to provide a framework for evaluating the predictive validity of model forecasts for COVID19 outcomes as data become sequentially available, using the IHME prediction of daily deaths as an example. Given our goal is to provide an evaluation framework, we treat the IHME model as a black box and examine the projected numbers of deaths per day in light of the ground truth to help begin to understand the predictive accuracy of the model.