Thread by @ProfDFrancis

What do you think of this reasoning?

Question 1.

If *most* (i.e. 51% or more) healthcare workers are getting Covid infection in the same way as the general population, how high can the rate in healthcare workers be, consistent with that?

Hint

Suppose everyone in the world gets Government Furlough cheques of £100/week.

Suppose I get these same Government Furlough cheques.
But also my parents give me some money every week.

How high could my total income per week be, consistent with the above?

Holy cow.

I sure hope it is better converted to $$$$.

People are much better with money than they are with mathematical thinking.

Even when they are exactly the same question. How did we do, as a human race?

Question 2.

Think about who was locked down at home versus who travelled to work, during the study

Who is locked down at home?

So, using the $$$ version, since we made an utter dogs dinner of the proportion calculation...

If the govt is handing out £100 weekly cheques
And my mum is handing out her own special supplement to her favourite son.

and THE GENERAL POPULATION NEVER SHOWS UP TO COLLECT THEIR CHEQUES

How many times larger can my income be than the general population?

And no the government isn't going to mail you your cheque, or pay it straight into the bank, in my thought experiment.

Just as the coronavirus on the metro isn't going to get sucked into a syringe by a drone, and blown up your nose, if you stay at home.

Sorry @glennGalen - thank you for asking me to clarify what I mean by Health Care Workers. The above remark was a criticism of my thread, shown here, which is an analysis of a paper in the Lancet from an experiment conducted at Barts Hospital, London.

https://twitter.com/ProfDFrancis/status/1259401640928595968

So what do you think of the first three lines of the remark?

Is it

But never mind about that.

Instead, mind about this!

wtAf?

11.6 fold?
Not 11.5, then? Nor 11.7?

Well at least he had the courtesy to present a link so that we could check the source that he had failed to understand.

He's taken one good habit from Public Health England, then.

Which is good.

I know you want to click the link, but you can't. I've just given you an image.

I hope you are shivering in anticipation?

What do you think the paper will be?

Options:

Randomized controlled trial

Case-control study of age/sex/*travel-habit*/etc matched health care workers and other workers

Cohort study

Just asked some people

Just as a sidebar, some people have raised some nice questions on Q1.

Yes, both of you are correct. But far too advanced for the simple point I was making.

*EVEN IF* Healthcare workers are travelling on the metro no more than the general population, and therefore catching the same amount of covid that way,

They could STILL get an extra "almost-as-much" infection rate from patients, and STILL fulfil the requirement of "Most staff infections coming from non-patient contact"

i.e. 2.0 (or just under it) is the limit I was looking for.

HOWEVER as I think you are both pointing out, the general population is being locked down at home, and healthcare staff are EXACTLY the opposite, honour-bound to come to work.

*At the bedside* most places now have PPE, and staff are careful. But the rest of the day, they suffer the same risk as everyone else.

Anyway, back to Question 2 (as I have retrospectively labelled it now).

Where did the 11.5-fold infection rate amongst staff, that was claimed by this guy, come from?

Oh, looks good.
I've heard of these things.
Cold Spring Harbor - that's something to do with DNA, isn't it?

Yeh but no.

Actually, it is an expertly done study, but *not* to compare the relative incidence in health care workers versus the general population.

It is OBVIOUSLY not an RCT (god knows why anyone clicked that)

medrxiv.org/content/10.110…

The stats, I consider to be pretty fancy and thorough!

HOWEVER they are careful scientists and made sure to make their statement clearly.

It was the Twitter twit that failed to understand the distinction between

"risk in a group of getting infected with Covid"

and

"risk in those using the app, of being tested for Covid, found positive, and reporting it on the app"

In fact this shows 2 things that real scientists do.

1. Round off a number when you know the relevant error bar is much, much wider than the error bar you calculate.

And

2. Report what you were able to calculate,
EVEN IF
that is not what you and everyone else want to know.

This is why scientists don't scream and shout at each other as much as politicians.

They may completely disagree on interpretation, but they know the limits to which their experiments and analyses should be considered convincing by intelligent-but-disagreeing counterparties.