The lockdown policy debate and one tiny
mathematical error.

An educational thread

1/n

Covid 19 daily deaths peaked on April 8 and
this is good news. The epidemic is under
control. The lockdown has worked.

Or has it?

A school of thought (incidentally affiliated
with the political right) begs to differ.

https://twitter.com/JohnRentoul/status/1252225759034425344?s=20
2/n

The "dissidents" contend that the epidemic peaked
BEFORE the lockdown was introduced, therefore the
lockdown was an unnecessary measure which only served to damage the economy. If the dissidents were correct, the policy implications would be huge.

In this thread...
3/n

I inspect the dissidents' central argument.
I show that it is based on a mathematical
error and therefore is invalid.

I also explain why their theory contradicts
broader empirical evidence.
4/n

First up, the argument itself.
The lockdown became effective on MAR 23.
The mean time from infection to death is 21
days. Therefore the deaths should have peaked
on APR12-APR13. But they did on APR8, see Fig.
5/n

Moreover, visual inspection of the deaths
curve suggests that the deaths began to
flatten out around March 30, MUCH earlier
than one would've expected based on the time
to death figure.
6/n