You Thought The ‘R’ Number Was Exact

From The Times – reported in the 30 January 2021 issue of The Week

Numbers influence social policy, says Ed Conway, but none have had such a huge impact on our lives as the “R number”. We know it’s a measure of how many people, on average, someone with Covid is likely to infect. We know it determines whether lockdown can be lifted. Yet few know how it’s calculated.

Far from deriving from some data-crunching formula, it’s the product of negotiation. Every week a group of academics from 11 different institutions meet online, each making a case for what he or she suspects the reproduction rate to be. These judgement calls, which often differ wildly, are then combined into a kind of average… and hey presto. R is effectively an educated guess.

Experts are baffled that ministers set such store by it: “no other leading nation” has let it dictate policy in this way. But having been slated at the start of the pandemic for failing to follow the science, the Government overcompensated: it thought that fixating on a “scientific” metric like R would silence the critics. Yet there’s nothing scientific about investing a single data point with more relevance than it deserves.