This paper used by Sage suggested 400 of 1600 positives were false. Still happy to have your school child home under house arrest for two weeks?

[Treesofwood]

Big problem with false positive us unnecessary self isolation for the person rested. Now it can lead to 300 children also being asked to self isolate for 2 weeks. This paper suggests when numbers are low, which they are at the moment, falso positives are a big problem. The more we test, the more we find them. www.gov.uk/government/publications/gos-impact-of-false-positives-and-negatives-3-june-2020
And the more children miss education and even being allowed to breathe fresh air if other threads on here are something to go by.
Obviously this is not a peer reviewed paper, but it is of enough interest and reliability to be used by Sage. Interested to hear thoughts, including if I have actually totally misinterpreted it.

“ Are we really meant to say “look, you’ve had a positive test, but it’s possible it could be false!... so just go about your daily business as normal.”?”

No one has suggested that

“ False positives, false negatives - maybe they just even themselves out. ”

Maybe they do in terms of national statistics, but this is individual lives we are talking about, and the impact on those who are isolating due to false positives, or not isolating due to false negatives, has real implications

Op, you sound, i'm afraid, like the parent type who will be sending their ill kids into school regardless of the rest of us. And probably also thinks vaccines are evil. In other words, batshit.

Just take the bloody test if you are ill and protect the rest of us. I would very much rather you and other deniers get over yourselves and test so that I have the least amount of children possible coughing, sneezing on tables and books I will then clean and mark and can get on with teaching without being as worried. If you refuse to test, your child should not be in school and you should not be in a workplace, for the sake of all the other people who are not David Icke.

@MrBucket

But that’s the implication of what @Treesofwood is suggesting. If isolating false positives is unreasonable, it follows that isolating all positives is unreasonable, as it’s impossible to tell the difference!

My point being I guess @SheepandCow that posters on MN can’t close the borders. So saying we need to follow NZ’s approach on here numerous times won’t do anything to help make that happen.

So what’s the alternative? Better tests take time to develop so in the meantime what do you propose as the solution?

False positives are an issue. If, as on the day on the paper, one quarter of cases were false positives it now doesn't actually only impact the person and handful of close contacts. It could close entire year groups, or even tip a decision onto closing a year. That could be 240 people isolating, and parents unable to work on just one out of 400 false positives in one day. Repeat daily, and assume a fair number of the 400 are kids and its a massive impact. For no actual benefit. As no one was actually ill.

Phleb since when did discussing societal and individual impact of government papers become batshit?

Just take the bloody test if you are ill and protect the rest of us

Given someone is ill and they come up positive, then there is a good chance they have Covid-19

If someone is not ill but has been a contact (eg at school) with someone who has tested positive (as above), and they come up positive, then there is less chance it is Covid-19

If someone is part of a mass screening programme, and they test positive, then there is far less chance it is Covid-19 - if the test used is one of the more unreliable lateral flow tests.

(So those positives should be followed up )

There should also be proper help - financial etc - to encourage people to self isolate - and to ensure that positive tests are confirmed.

Because 2 weeks self isolation is of major concern to some people - especially with regards to job security, income etc.

False positives are an issue

Did you see the ONS figures?

The modelled estimates for the latest six-week period are based on 183,994 swab tests collected over this period. During these weeks, 89 people from 84 households tested positive

So not many people testing positive - relative to a large number of tests in a random sample of the population

@phlebasconsidered

Op, you sound, i'm afraid, like the parent type who will be sending their ill kids into school regardless of the rest of us. And probably also thinks vaccines are evil. In other words, batshit.

Just take the bloody test if you are ill and protect the rest of us. I would very much rather you and other deniers get over yourselves and test so that I have the least amount of children possible coughing, sneezing on tables and books I will then clean and mark and can get on with teaching without being as worried. If you refuse to test, your child should not be in school and you should not be in a workplace, for the sake of all the other people who are not David Icke.

What the fuck is all this ‘denier’ stuff that’s being thrown at people? Someone questioning policy does not make them a Covid denier. No one on this thread has said Covid doesn’t exist (unless I’ve missed it). People are having completely sane and rational discussions about the policies in place. Calling someone a ‘denier’ because they are discussing government and public health policy quite frankly makes the one levelling the accusation look a little bit dense.

“ But that’s the implication of what @Treesofwood is suggesting. If isolating false positives is unreasonable, it follows that isolating all positives is unreasonable, as it’s impossible to tell the difference!”

No, there might be other options, which are being discussed on the thread. It’s worth discussing, given the implications for many people of isolating. Just as it is worth discussing false negatives given the implications for vulnerable people. Many people clearly think the negative consequences of many people isolating due to false positives are worth bearing - so what if some people lose their livelihoods (for example), it is a price worth paying. I don’t necessarily believe that, and I’m not a “Covid denier”, I just think we should be allowed to examine the consequences of decisions like this

False positives are going to mean people are isolating unfairly and that sucks. But there's no better test at the moment and we're not managing to test all the people who need to be tested at the moment so a second test for all who test positive seems out of reach just now.

Currently we have two options, ignore positive results in case they're false positives and tell people to crack on (in which case, why bother testing?) Or accept that some people will be isolating unnecessarily. Given that most positives won't be false and the potential consequences of letting infected, asymptomatic people socialise freely, I know which I would pick if I was in charge.

@MrBucket

“ Are we really meant to say “look, you’ve had a positive test, but it’s possible it could be false!... so just go about your daily business as normal.”?”

No one has suggested that

That hasn't been suggested but it has been suggested elsewhere that in asymptomatic cases, a follow up test is done to confirm

that's not right OP.
The paper states the MEDIAN false positive rate was estimated to be around 2.3%. The range was given as 0.4 - 8%.
So no where near the 25% you are suggesting.

I actually think the specificity of the test is better than the sensitivity form other research I have read, which means that you will get more false negatives which could be a problem.

False positives are going to mean people are isolating unfairly and that sucks. But there's no better test at the moment and we're not managing to test all the people who need to be tested at the moment so a second test for all who test positive seems out of reach just now

Not very world beating, is it...…...

Perhaps if the argument were rational, instead of of peppered with "house arrest" implications? There is a certain type of U4T supporter that posts like this with the sole aim of undermining testing, mask wearing and other mitigating measures and this op is one of them, it strikes me. Otherwise why be inflammatory and go all "house arrest"? It's perfectly possible to question data without that. Although it helps to have read the whole report.

I admit i'm touchy though as there is a very vocal group of parents who are determined to abandon masks and tests in my area which doesn't exactly fill me with joy as a teacher. My local area is known for idiocy though - it had UKIP local councillors.

If you're asymptomatic and have positive test, a second test would eliminate the risk of a false positive. I would do that if I was asymptomatic and hadn't been in contact with someone with COVID - although I would pay for it.

@phlebasconsidered

Perhaps if the argument were rational, instead of of peppered with "house arrest" implications? There is a certain type of U4T supporter that posts like this with the sole aim of undermining testing, mask wearing and other mitigating measures and this op is one of them, it strikes me. Otherwise why be inflammatory and go all "house arrest"? It's perfectly possible to question data without that. Although it helps to have read the whole report.

I admit i'm touchy though as there is a very vocal group of parents who are determined to abandon masks and tests in my area which doesn't exactly fill me with joy as a teacher. My local area is known for idiocy though - it had UKIP local councillors.

‘House arrest’ is a turn of phrase. Whether the OP is inflammatory or not, the discussion on the thread remains valid.

Yes, a purposefully inflammatory one. So it does impact on the focus of discussion. As any student can tell you - a turn of phrase matters. They could have used isolation, staying indoors, within the home, self-isolating, or "protecting others by staying inside". Which is also a "turn of phrase" but implies the exact opposite to "house arrest". Language matters. The post is not impartial and chat about data needs to be. Unless it's being swung to manipulate.

@phlebasconsidered

Yes, a purposefully inflammatory one. So it does impact on the focus of discussion. As any student can tell you - a turn of phrase matters. They could have used isolation, staying indoors, within the home, self-isolating, or "protecting others by staying inside". Which is also a "turn of phrase" but implies the exact opposite to "house arrest". Language matters. The post is not impartial and chat about data needs to be. Unless it's being swung to manipulate.

Regardless of the turn of phrase in the OP, the discussion throughout the thread remains valid. Calling people who wish to discuss the policy that affects lives ‘deniers’ is equally as inflammatory and is an attempt to shut down discussion.

Mosscarpet you haven’t understood the way the numbers works.

If the chances of getting a false positive on each individual test are very low but you are testing far more negative people than positive people then you can easily end up in a situation where a quarter of your positive tests come from negative people.

The OP has gone through the numbers upthread - whether or not you agree with her about whether it’s a deal breaking problem, her numbers aren’t wrong.

Do you believe the op started this as a discussion when she had that in the title? Really?
Some discussion has been reasoned. The title is not - and neither was the op, which is what I was addressing.

The OP has gone through the numbers upthread - whether or not you agree with her about whether it’s a deal breaking problem, her numbers aren’t wrong

True - but then again, if you look at the ONS numbers, there were 180,000 tests taken and only 89 positive people.

I wonder how many of those were false positive?

Imagine you find a large tribe in the depths of the Amazon who has never had contact with the outside world. You give all ten thousand of them Covid tests. With a 0.4% false positive rate you’d get 40 positive cases, 100% of which were false positives. And 9,960 negative tests, which were 100% correct even if the official false negative rate of the test was 20%.