Fig. 17.

Long-term forecasts derived using the GRM by estimating parameters$r$, $p$ and $K$ with quantified uncertainty when the model is fitted to an increasing length of the growth phase (40, 60, …, 140 days) of a synthetic daily incidence curve simulated using the same GRM model with parameters $r=0.2,p=0.8\text{,}a=1\text{,}\text{and}K=1000$. Using only data of the early epidemic growth phase (before the inflection point occurring around day 50), the model is underdetermined and significantly underestimates the incidence curve. Forecasts are gradually improved particularly when the model is calibrated using data past the epidemic's inflection point. The cyan curves correspond to the uncertainty during the model calibration period while the gray curves correspond to the uncertainty in the forecast. The mean (solid red line) and 95% CIs (dashed red lines) of the model fit are also shown. The vertical line separates the calibration and forecasting periods.