Targets and horizons

There is no obligation to submit forecasts for all suggested targets or horizons, and it is up to you to decide which you are comfortable forecasting with your model. Please take care when submitting the forecasts to be clear which target and horizon you are using: use this page and the formatting guide.

Targets

Targets

We are currently focused on two forecast targets:

• New Covid-19 cases
• New Covid-19 deaths

You can submit forecasts for only cases or deaths, or both targets.

We only use incident forecasts: the count of new cases or deaths per week. We do not use cumulative (running total) forecasts. This varies from other forecast hubs.

In future we are likely to ask for forecasts of health system burden indicators.

Truth data

We evaluate forecasts against ECDC data, and we recommend using this dataset as the basis for forecasts. While ECDC data may in some cases differ slightly from individual national datasets, sharing a common dataset across all forecast models means we can clearly compare the differences between models.

• Data are available to download here
• Use the weekly_count variable for incident cases or deaths
• Data are reported by week, defined in ECDC year-week format

ECDC data are collected between Monday and Wednesday for the whole of the preceding week and published on Thursdays. For example, new cases and deaths between Monday 4th January 2021 to Sunday 10th January were reported as the first ECDC week of 2021 (Week 2021-01). Data for that week was first published on the following Thursday 14th January. The ECDC provide a data dictionary, information on data collection, and more detail on individual country data.

Horizon and frequency

Horizon

We use horizons of between 1 and 4 weeks ahead, in the ECDC year-week format. You can submit a forecast for any combination of horizons up to 4 weeks ahead.

Date format

Forecast horizons should use the ECDC year-week format. For example:

• A 1 week ahead forecast made on Friday 1st January 2021 should cover the seven days including Monday 4th January to Sunday 10th January (ECDC year-week 2021-01)
• A 4 week ahead forecast made on Friday 1st January would include the period Monday 25 January to Sunday 31st January 2021 (ECDC year-week 2021-04)

Note that ECDC year-week 2020-53 covered Monday 28th December to Sunday 3rd January, so ECDC year-week 2021-01 started on Monday 4th January. You can find two csv files converting ECDC year-weeks to their start and end dates, and any date to its ECDC year-week, in the template folder.

Frequency

Forecasts can be submitted once per week only. Submission can be at any time between Thursday and Monday (23:59 GMT).

Location

You can submit a forecast for a single country, or any combination of the 26 EU nations and the UK.

Currently we do not accept sub-national forecasts. Sub-national country datasets can be incompatible with each over and over time, making comparisons between forecasts unclear.