COVid19-What's wrong with UK?

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NickFaulks
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Re: COVid19-What's wrong with UK?

Post by NickFaulks » Thu Mar 11, 2021 9:48 pm

John McKenna wrote:
Thu Mar 11, 2021 9:18 pm
As I've said before - it's the false negatives that are the real problem with falsies.
Surely it is obvious that they are both problems. If there were no actual positives at all, but enough false positives to justify shutting down the country, you don't think that would be a problem?
If you want a picture of the future, imagine a QR code stamped on a human face — forever.

John McKenna

Re: COVid19-What's wrong with UK?

Post by John McKenna » Thu Mar 11, 2021 11:12 pm

NickFaulks wrote:
Thu Mar 11, 2021 9:48 pm
John McKenna wrote:
Thu Mar 11, 2021 9:18 pm
As I've said before - it's the false negatives that are the real problem with falsies.
Surely it is obvious that they are both problems. If there were no actual positives at all, but enough false positives to justify shutting down the country, you don't think that would be a problem?
I agree that both are problems.

False negatives are a direct problem for the surpression of the spread of the virus, hospitalisations & deaths and its impact on the numbers in the data that are being scrutinised to determine if the above schedule can be adhered to.

False positives impact financially on the persons who have been wrongly diagnosed as being infected if they self-isolate. They also may tip the numbers in the data wrong way for the hoped-for full-throttle opening up on 21st June.

Let's hope the standard of testing is now good enough to give reliable figures and minimise both false positives and negatives and that they do not turn into -

"Scylla and Charybdis - mythical sea monsters... Homer sited them on opposite sides of the Strait of Messina between Sicily and Calabria. Scylla was rationalized as a rock shoal (described as a six-headed sea monster) on the Calabrian side of the strait and Charybdis was a whirlpool off the coast of Sicily. They were... close enough to each other that they posed an inescapable threat... avoiding Charybdis meant passing too close to Scylla and vice versa. According to Homer's account, Odysseus was advised to pass by Scylla and lose only a few sailors, rather than risk the loss of his entire ship in the whirlpool." (Wiki)

NickFaulks
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Re: COVid19-What's wrong with UK?

Post by NickFaulks » Thu Mar 11, 2021 11:37 pm

John McKenna wrote:
Thu Mar 11, 2021 11:12 pm
False positives impact financially on the persons who have been wrongly diagnosed as being infected if they self-isolate.
The idea that the effects of being isolated are "just about money" is the most dangerous myth of this whole catastrophe. It is clear that the damage to individuals, families and society as a whole goes far deeper than that, and we haven't seen the half of it yet.
Let's hope the standard of testing is now good enough to give reliable figures and minimise both false positives and negatives
You can hope what you like, but the Royal Statistical Society isn't buying it.

https://rss.org.uk/RSS/media/File-libra ... h-2021.pdf
If you want a picture of the future, imagine a QR code stamped on a human face — forever.

John McKenna

Re: COVid19-What's wrong with UK?

Post by John McKenna » Fri Mar 12, 2021 12:07 am

Thanks for the link, Nick. (I will be perusing it.)

As for 'isolation' - we chess players know the weaknesses of the isolated pawn - it is the lockdowns that have caused most of that. And, of course, there's a high price to pay in terms of mental, physical and financial health.

I believe it has been promised that there will be no more national lockdowns.

"While/where there's life there's hope. So long as there’s a chance of success, there’s hope that it will happen. (This ancient saying goes back to the time of the Greeks and Romans)."

NickFaulks
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Re: COVid19-What's wrong with UK?

Post by NickFaulks » Fri Mar 12, 2021 10:23 am

John McKenna wrote:
Fri Mar 12, 2021 12:07 am
I believe it has been promised that there will be no more national lockdowns.
Several times, typically just before the next one.
If you want a picture of the future, imagine a QR code stamped on a human face — forever.

Matthew Turner
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Re: COVid19-What's wrong with UK?

Post by Matthew Turner » Fri Mar 12, 2021 10:58 am

False positives and False negatives are clearly both problems, but they are known problems.
So when we say that they are x positive PCR tests and y negative PCR tests we can pretty accurately work out the number false results.

Lateral flow tests are a slightly different matter. Yes they are less reliable, so there will be more false results, but from a planning point of view it is difficult to know how reliable they are. An obvious problem being how will reliability change when a test is carried out at home as compared to a GP's surgery.

Matthew Turner
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Re: COVid19-What's wrong with UK?

Post by Matthew Turner » Fri Mar 12, 2021 12:13 pm

Consider this example
0.5% of people have coronavirus (people with coronavirus behave the same as those without)
An instant test is 97% accurate
40,000 people want to attend a football match

Therefore, of our potential attendees 200 have coronavirus

Now we make a rule that you must have a negative test at the ground
We have 38606 true negatives
6 false negatives
194 true positives
1194 false positives

One could argue that the test is horrendously bad, because out of the positives only 1 in 7 actually have the disease, but the upshot is that the game goes ahead with a crowd of 38612 with only 6 coronavirus carriers.

John McKenna

Re: COVid19-What's wrong with UK?

Post by John McKenna » Fri Mar 12, 2021 12:21 pm

Matt, I don't know where you got your figures from but I've heard experts say that the number of false negatives is usually greater than the number of false positives (and I repeat - FALSE NEGATIVES ARE MORE DANGEROUS). Nick gave a link in one of his posts, further above, that contained -

"Royal Statistical Society COVID-19 Taskforce: Statement on the need for transparency about information on secondary pupils’ uptake of Lateral Flow Testing, PCR-corroboration, cyclethreshold-values (proxy for viral load) & genomic analyses..."

https://rss.org.uk/RSS/media/File-libra ... h-2021.pdf

It has figures for false positives & negatives in the above context and, as Nick has stated, it shows that the number of false positives can exceed the number of false negatives if the number of infected people is very low in the tested population.

What must be remembered is that the testing of secondary school pupils is not the same as testing adults in the general population (see contents of Nick's link).

Also, remember that in June 2020 this was the situation just before the economy was reopened on 4th July -

"The UK has recorded its lowest number of daily confirmed coronavirus cases - 958 - since the lockdown began.
The number of daily virus deaths also fell to 15, the lowest figure since 15 March..." (BBC News 22 June 2020)

https://www.bbc.co.uk/news/uk-53141763

Is the UK Government hoping for a similar situation to be achieved by 21st June 2021? (Their scientific and medical advisers seem to be calling for it.)

The big difference between spring 2020 and 2021 is the vaccine rollout. In spring 2020 the UK was entering lockdowm and "ramping up" testing.

Now this spring the UK is exiting an equivalent lockdown with a much greater testing capacity and an ever-increasing number of people vaccinated.

Nick might like to have a look at the following -

"Covid-19: How reliable are test results?"

https://commonslibrary.parliament.uk/co ... t-results/
NickFaulks wrote:
Fri Mar 12, 2021 10:23 am
John McKenna wrote:
Fri Mar 12, 2021 12:07 am
I believe it has been promised that there will be no more national lockdowns.
Several times, typically just before the next one.
They sound as if they really mean it this time and due to the above-mentioned differences between this year and last they're ready to stake their reputation on what amounts to the slogan - no going back to national lockdowns.

If there is another national lockdown I hope they'll be prepared to resign from governing the country.

I leave with two words of warning - porous border. (They may ultimately be the making or the breaking of the United Kingdom in the struggle with this virus).

Oh, and you might like to know that a BBC reporter on the World Service last night said that things in China were pretty much back to normal and it was as if the pandemic had never happened.

Matthew Turner
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Re: COVid19-What's wrong with UK?

Post by Matthew Turner » Fri Mar 12, 2021 12:30 pm

John McKenna wrote:
Fri Mar 12, 2021 12:21 pm
Matt, I don't know where you got your figures from
I think re-reading my post should help you with this one.

John McKenna

Re: COVid19-What's wrong with UK?

Post by John McKenna » Fri Mar 12, 2021 12:44 pm

The best I can come up with, Matt, is that they are a reworking of the kind of figures given in Nick's link to the Royal Statistical Soc. Take it/them or leave it/them.

Obviously we are to also draw our own conclusions on what they amount to.

Would you be prepared to go to Euro 2020 fixtures at Wembley/Glasgow this summer if you were in a crowd of about 40,000? (I think I heard only 10,000 will actially be allowed in to each match.)

Would you estimate that would be more, or less, risky than going back to school?

Matthew Turner
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Re: COVid19-What's wrong with UK?

Post by Matthew Turner » Fri Mar 12, 2021 12:54 pm

Governments and individuals have to weigh up risks and benefits. There are risks involved in children returning to school and risks involved in attending a football match. I would be unlikely to attend a large football match because I could get similar benefits by watching it on the telly.
In my opinion, there are massive benefits to children returning to school, so this should happen even if there are considerable risks involved.

Kevin Thurlow
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Re: COVid19-What's wrong with UK?

Post by Kevin Thurlow » Fri Mar 12, 2021 12:59 pm

With any rapid test, you want more false positives than false negatives. Colleagues who did testing of restricted drugs would run a quick screening test on the many thousands of samples they received. This eliminated 95 % plus of the samples. Any testing positive were then analysed with the expensive, time-consuming analysis, at which point lots of the positives disappeared. e.g Codeine, heroin and cocaine (etc) should give positive results for the quick test (as they're chemically similar), but deeper analysis will accurately identify what's there and how much. So whereas the long-winded analysis should give the right answer, the really quick one won't be as good, but you find out now, rather than waiting. What was worrying was that some people were saying that they would believe the lateral flow test, even if the proper test contradicted it. (Same as people believe the "home drug testing kits" which are advertised widely.)

Of course in any test the analyst might (very, very infrequently) get it wrong.

John McKenna

Re: COVid19-What's wrong with UK?

Post by John McKenna » Fri Mar 12, 2021 1:02 pm

Thanks for your candid answer, Matt.

Edit - and for Kevin's knowledgeable contribution.

Mick Norris
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Re: COVid19-What's wrong with UK?

Post by Mick Norris » Tue Mar 16, 2021 9:23 am

The inside story of the government's battle against the virus
But one senior politician who attended at the same time says: "The early meetings with the prime minister were dreadful." And inside Downing Street, senior staff's concerns about the government's ability to cope grew.
The prime minister believed that another lockdown would be a disaster and wanted to avoid it at all costs - but for many of those involved in making the decisions, his hostility to tightening the rules again was frustrating, dangerous and political.
"The PM was saying the Tory Party won't swallow it," one tells me. "Everyone else felt, we know we are going to have to do a lockdown."
Any postings on here represent my personal views

NickFaulks
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Re: COVid19-What's wrong with UK?

Post by NickFaulks » Tue Mar 16, 2021 1:36 pm

We do need to remember that all of these anonymous quotes come from people preparing the ground for an inquiry which they fear they cannot delay forever ( although they will certainly try! ).
If you want a picture of the future, imagine a QR code stamped on a human face — forever.

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