Fig. 2: Illustration of the analytical framework.

This figure highlights the analytical framework presented in the main text. Part A highlights the “most current” approach, which is used to select the data shown in Fig. 3. Part B highlights the “month stratified” approach used for Figs. 4 and 5. The Y axis shows the number of weeks of extrapolation for each scenario, while the x axis shows a range of model date—the date on which a model was released. The thick band in each plot highlights the 4-week window of model dates used for each extrapolation week value. The thin line shows the period for which each set of models is extrapolating before errors are calculated. In the top panel, the most recent 4 weeks of model dates are used for each extrapolation length. Therefore, for 1-week errors, models from January and February 2021 were used, whereas for 12-week errors, models from October and November 2020 were used. In the bottom panel, models from October are used in all cases. The analytic strategy highlighted in the top panel provides the most recent evidence possible for each extrapolation length. The strategy at the bottom allows for a more reliable assessment of how errors grow with increased extrapolation time.