Professor Norman Fenton (university of London)

[denso13]

Here is a paper stating how it is done and what is expected.
https://assets.publishing.service.g...9_Impact_of_false_positives_and_negatives.pdf

And it says "The UK operational false positive rate is unknown. There are no published studies on the operational false positive rate of any national COVID-19 testing programme."

 

[EFLImpudence]

And it says "The UK operational false positive rate is unknown. There are no published studies on the operational false positive rate of any national COVID-19 testing programme."

Then how can you believe the number of positive tests?

It must mean therefore that no one knows how many people have covid but are asymptomatic - and possibly that there is no such thing. Perhaps only people who are ill with covid have covid. Would you be pregnant if a test said you were?

Also then, obviously people who believe everything they are told do not have sufficient knowledge to dismiss as simply wrong any opinions by those who do not believe everything they are told.

 

[JP_]

just watching the video now. It's official, listening to a mathematician talk about covid is even more boring than listening to a plumber.

 

[IT Minion]

And it says "The UK operational false positive rate is unknown. There are no published studies on the operational false positive rate of any national COVID-19 testing programme."

Following their method:

DHSC figures [3] show that 100,664 tests were carried out on 31 May 2020 (Pillar 1 and 2 RT-PCR tests). 1,570 of those tests were positive for SARS-CoV-2 (1.6%). The majority of people tested on that day did not have SARS-CoV-2 (98.4% of tests are negative).

The latest data gives (from Testing | Coronavirus in the UK (data.gov.uk)):
20-04-2021
PCR Tests conducted: 288,328
Positive tests (PCR AND Lateral Flow): 2,029

Now, let's try to work out the maximum false positive rate. Let's assume that none of those results were from lateral flow tests, so all the positive results were from PCR tests. Let's also assume that none of those peope really did have Covid-19, every single one of those tests was a false positive. That give us a maximum false positive rate around 0.7%. The real false positive rate is going to be lower than that as some positive results would be from lateral flow tests and some would be from people who really do have Covid-19.
If we work it the other way, so assuming we had a false positive rate of 2.3% that means we should have picked up false-positive 6,631 cases in addition to any real positive cases.

That was the most recent day I found Tests and outcomes for. Let's look further back to the lull between the first and second waves where we had plenty of testing but low levels of the disease.

16-7-2020
PCR Tests conducted: 150,975
Positive tests (PCR Only): 642
~0.4%

Assuming the worst case, i.e. none of those were real positives, that gives a worst possible case of 0.4% again assuming that there were no people with Covid-19 at all identified that day and every single positive result was a false positive.

There are even lower numbers than that, the lowest i've seen was the 21/07 which was around 0.33% positive results for PCR but i haven't done a complete sweep.

So, what does this show us? That PCR can't have a false positive rate of 2.3%. The false positive rate could not be above 0.33% on the 21st of July. It seems reasonable to assume that the false positive rate hasn't increased since, especially as back then we were using roughly 2/3rds our testing capacity rather than using 1/3rd our current testing capacity. It is more plausible that now the labs are less stressed they probably have fewer false positives.

Also then, obviously people who believe everything they are told do not have sufficient knowledge to dismiss as simply wrong any opinions by those who do not believe everything they are told.

I don't know. Look at the other videos.
<snip>
No, not my calculation, nor my video originally.
I am merely using the figures in the screen-grab.

That is how it is done.

 

[John the plumber]

just watching the video now. It's official, listening to a mathematician talk about covid is even more boring than listening to a plumber.

I dunno about that to be honest,although nearly as boring listening to someone seeking help to support a plastic step when it’s stepped on

 

[ajohn]

The video is a miss use of statistics and misses the point of doing the tests despite the errors. The basic idea is to get some proportion of people with covid into isolation particularly if they are going to mix with a lot of people.