Forecasting as an epidemiological problem

Understanding, evaluating, and improving forecasts of infectious disease burden

Forecasting in infectious disease epidemiology

Metcalf & Lessler, Science, 2017

Using models for statements about the future

Modelling the future can help decision making:

• how many beds do we need?
• where should we allocate vaccines?
• where should we trial vaccines?

However:

• not all modelling is prediction
• not all modelling of the future is forecasting

Different ways of modelling the future

• Nowcasts make statements about current trends based on partial data

• Forecasts are unconditional statements about the future: what will happen

• Scenarios state what would happen under certain conditions

Why nowcast/forecast?

• to create situational awareness
  • nowcast: where are we now?
  • forecast: where are we heading?

CDC use of influenza forecasts

CDC: About Flu Forecasting

Forecasts are usually probabilistic

• Because the future is uncertain, it is natural to express predictions in probabilities, e.g. there is a X% chance of exceeding Y hospital admissions.

Your Turn

1. Load some forecasts we have generated and visualise them alongside the data.
2. Explore different ways of visualising forecasts to assess how good the model performs at forecasting.

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