Why the math behind the UK’s ‘COVID alert levels’ makes no sense

Why the math behind the UK's ‘COVID alert levels’ makes no sense

During these uncertain times of coronavirus lockdown, we are expected to look towards our leaders for advice and guidance. Critically, the instructions should be as simple and accurate as possible, to ensure that people follow the advice. Unfortunately, on May 10, Prime Minister Boris Johnson’s Twitter account released a number of “infographics” which are, quite frankly, baffling.

At the time of writing, the infographics are still available and no further explanation has been offered. The goal of the infographics was primarily to introduce the idea of the “COVID alert levels,” which go from one (COVID no longer present in the UK) to five (material risk of overwhelming the healthcare system). It’s a nice idea but, unfortunately, it’s practically useless.

For starters, the choice of one to five scale is quite arbitrary. To see why, consider the joke in the movie This is Spinal Tap that some amplifiers are better because they go all the way to 11 instead of 10, even though this is really just a random number.

Read: [Using ‘personalized AI’ to end coronavirus lockdown is a stupid, cruel idea]

Of course, the choice of scale is a subjective and an aesthetic one – not an actual problem. It is when you analyze the graphs and equation behind it that things get murky.

Bewildering equation

The alert level was explained by an equation: “COVID alert level = R (rate of infection) + number of infections.” Sadly, the equation is nonsense for a number of reasons. To understand why, let’s consider something we call units.

Why the math behind the UK's ‘COVID alert levels’ makes no sense