# The value of R

Discussion in 'Personal' started by S1a3t5u7r9n, May 28, 2020.

2. ### S1a3t5u7r9nEstablished commenter

Wait for it the R value will start to increase
We will remain at Level 4 even though Boris has introduced relaxations

3. ### S1a3t5u7r9nEstablished commenter

Can I remind you
R is increasing
Can anybody tell me how it is measured
Or is it political?

5. ### S1a3t5u7r9nEstablished commenter

I am still no clearer on how it is measured

6. ### florian gassmannStar commenter

As I understand it, R is based on historic data such as the daily death rate, daily hospital admissions rate and daily positive testing rate, all of which gives a picture of what the R number was two to three weeks ago. Don't ask me how the separate data are combined - I have no idea and in any case I think there are many different ways of doing it, resulting in different values for R from different authorities. That is then projected forward to reach a figure for today, based on how far down the curve we now are compared with where we were two or three weeks ago.

If that sounds rather vague, it is probably because the calculation of R is a rather imprecise matter.

To get a more up-to-date value of R number, the ONS is testing random samples of population to see how many have the disease. I believe this will also eventually provide better regional and area data for R.

The following is probably a better explanation than anything I write:
https://www.healthknowledge.org.uk/...earch-methods/1a-epidemiology/epidemic-theory

Last edited: Jun 6, 2020

It is worked out backwards from different measurements. e.g. If the number of infected people stays more or less constant R is 1.

8. ### S1a3t5u7r9nEstablished commenter

Thanks for that
But what is the mathematical formula
And if it is calculated backwards is it always out of date?

The R number cannot be calculated in real-time.

Instead, scientists look at figures including positive tests, rates of hospitalisation and fatalities to work out an estimate of the rate of transmission. Different agencies use differing criteria, so I cannot give you a single equation, but read through this https://www.healthknowledge.org.uk/...earch-methods/1a-epidemiology/epidemic-theory

Or this is you are au fait with some higher maths. https://en.m.wikipedia.org/wiki/Basic_reproduction_number

Generally this creates a picture that covers roughly the past month. The accuracy of estimates should improve over the course as testing and tracing rates rise.

Last edited: Jun 6, 2020
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10. ### S1a3t5u7r9nEstablished commenter

I will study carefully

11. ### florian gassmannStar commenter

Prof John Edmunds (Dean of the Faculty of Epidemiology and Population Health, and Professor of Infectious Disease Modelling at the London School of Hygiene and Tropical Medicine) gave an interesting account of R on BBC R4 this morning. He maintains that the increase in R is largely driven by continuing infections in care homes and hospitals, and that the R in the community is pretty much flat-lining.

12. ### S1a3t5u7r9nEstablished commenter

This is my focus
How do you actually calculate R?

13. ### gainlyStar commenter

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14. ### S1a3t5u7r9nEstablished commenter

Yes I did
But can you explain it to me
Do you listen to the explanations given on TV
R is propaganda

15. ### S1a3t5u7r9nEstablished commenter

So wait and see what happens and adjust R

16. ### gainlyStar commenter

I thought you were a maths teacher. You should explain it to us.

Ciao

18. ### S1a3t5u7r9nEstablished commenter

Does anybody have an update on the R value
Who is responsible for publishing the R value?

19. ### florian gassmannStar commenter

If I remember correctly, SAGE considers at least ten different calculations of R from different sources (Imperial College, the London School of Hygene and Tropical Medicine, the team consisting of PHE and researchers from Cambridge UNiversity, and various others), plus epidemiological data such as hospital admissions, ICU admissions and deaths and the more immediate results produced by ONS direct sampling of the population, and then comes up with some sort of weighted average.

The latest official (but still unchanged) values for R, published on Friday, can be found here:

https://www.gov.uk/guidance/the-r-number-in-the-uk

As it says, the most likely value for R is in the middle of each given range, so 0.9 (range 0.8-1.0) for England in general, 0.8 for the East of England, and so on.

Last edited: Jun 15, 2020