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Surely the R value can’t be calculated?

(5 Posts)
hardheadedwoman Sun 03-May-20 14:58:41

So much importance has been placed on the R value and keeping it under 1.

However in order to calculate it you’d need to know how many people have got CV currently and how many people have previously had CV? We don’t have reliable stats due to lack of testing.

In the absence of reliable stats does anyone know what assumptions are made in the calculation?

OP’s posts: |
Northernsoullover Sun 03-May-20 14:59:29

No but I'm following with interest..

eveoha Sun 03-May-20 15:05:02

Not sure re these stats but think they’re another form of distraction - 😡

nellodee Sun 03-May-20 15:12:44

We can study the rate of change and see whether it is increasing or decreasing. And we know where 1 is on that scale. I think it we have an idea of how long people are infectious for, and we have a trusted metric that may not give total cases, but is reliable, and in proportion to total cases (such as hospital admissions, or deaths) then we can probably come up with a figure. So, very simply, if new cases halved in 2 weeks, and we knew people were infectious for a median time of 2 weeks, we would have an R0 of 0.5. If it took that long for cases to double, we would have an R0 of 2. I've used a very simple example, because we'd get into logarithms otherwise.

I don't think we do have a precise figure on the period of time people are infectious for, but we probably have something close enough to give it a good guess.

nellodee Sun 03-May-20 15:14:38

I think this is probably why they use hospital admissions. I think using deaths is more difficult because different age groups tend to survive for different lengths of time, whereas everyone tends to be hospitalised at about the same stage in the disease.

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