The Crystal Ball

Monday, March 1, 2021

A crystal ball or orbuculum is a crystal or glass ball and is associated with the performance of clairvoyance and the ability to predict future events.

Before the modern era, those who claimed to be able to see the future were treated with suspicion and branded as alchemists, magicians and heretics.  Nowadays we take it for granted that the weather can be predicted with surprising accuracy for a few days at least – certainly long enough to influence our decisions.

And weather forecasting is a notoriously tricky challenge because small causes can have big effects – and big causes can have no effects.  The reason for this is that weather forecasting is called a nonlinear problem and to solve it we have had to resort to using sophisticated numerical simulations run on powerful computers.

In contrast, predicting the course of the COVID-19 epidemic is a walk in the park.   It too is a nonlinear problem but much a less complicated one that can be solved using a simple computer simulation on a basic laptop.

The way it is done is to use the equations that describe how epidemics work (which have been known for nearly 100 years) and then use the emerging data to calibrate the model, so over time it gets more accurate.

Here’s what it looks like for COVID-19 associated mortality in the UK.  The red dotted line is the reported data and the oscillation is caused by the reporting process with weekend delays.  The solid red line is the same data with the 7-day oscillation filtered out to reveal the true pattern.  The blue line is the prediction made my the model.

And we can see how accurate the prediction is, especially since the peak of the third wave.

What this chart does not show is the restrictions being gradually lifted and completely removed by April 2020.

The COVID Crystal Ball says it will be OK so long as nothing unexpected happens – like a new variation that evades our immune systems, or even a new bug completely.

It has been a tough year.  We have learned a lot through hardship and heroism and that a random act of nature can swat us like an annoying fly.

So, perhaps our sense of hope should be tempered with some humility because the chart above did not need to look like that.  We have the knowledge, tools and skills to to better.  We have lots of Crystal Balls.