This is an analysis of forecasts made by participants of the UK COVID-19 Crowd Forecasting Challenge. Over the course of 13 weeks (from May 24 2021 to August 16 2021) participants submitted forecasts using the crowdforecastr prediction platform.

These forecasts were aggregated by calculating the median prediction of all forecasts. These aggregated forecasts (later denoted as “epiforecasts-EpiExpert” or “Median ensemble”) were submitted to the European Forecast Hub.

1 Prediction targets and observed values

Participants were asked to make one to four week ahead predictions of the weekly number of reported cases and deaths from COVID-19 in the UK. Figure 1.1 shows a visualisation of daily and weekly observed cases and deaths.

Visualisation of daily (bars) and weekly (line) reported numbers.

Figure 1.1: Visualisation of daily (bars) and weekly (line) reported numbers.



2 Visualisation of forecasts

Figure 2.1 shows the median predictions of all participants as well as the crowd ensemble. We can see that there is considerable disagreement between individual forecasters on most forecast dates.