Coronavirus testing

[asperity]

17 minutes ago, Confused52 said:

PHE were effectively responding to the SAGE action to remove uncertainty. They realised, correctly, that the experts on such statistical works are the ONS. The ONS survey is of people at random who are not known to have an infection. That is an important point because their estimate is based on a worst case interpretation of their results. The rate of 0.30% false positives assumes every positive case was false and therefore gives an upper bound and worst case value for tests using PCR. They seem to have used this convoluted method to avoid giving out multiple different values. I heard of this result on More or Less on Radio4 from Professor David Spiegelhalter who was asked what the false positive rate was.

The unsure bits you mention don't seem very uncertain to me the just seem scientifically cautious. For example, they could have included that they didn't check that people swapped samples with a known infected person just to be malicious. I suggest that they do know pretty well what the accuracy of the test is on random samples of mostly non infected people. When people have symptoms and have asked for a test they are going to show a lower error rate but the 0.30% error rate will still apply to those who are tested as contacts having not shown symptoms. That hopefully explains the point I made in the earlier post. The test also has false negatives and they are much harder to pin down as you can see.

I concentrated on the issue of false positives because there as a set of people claiming the false positive rate is high to make a claim that the epidemic is somehow overstated. 

I wouldn't say that it's being overstated Con, in fact I imagine that the number of people who have the virus is a multiple of those actually found to have tested positive. But we can carry on with the daily hysterical reporting of how many thousands have been tested positive (inaccurately called "cases" as if they are all at death's door), which is about 4.5% of people tested without putting it into context.

Meanwhile we have people being labelled as "covidiots" as if these are a separate set of people to those who have tested positive, presumably through no fault of their own. So if people are catching the virus, even though they are following all the rules, doesn't this show that the rules are a waste of time? Or maybe "covidiots" are somehow immune and, if they are, shouldn't we be studying them to find out if the immunity can be passed on to everyone else?

[asperity]

26 minutes ago, Observer II said:

In order to make the suicidal return to schools more acceptable,  seems the Army will be used to mass test students, presumably to screen them prior to entry each and every day.   😷

I've told you a million times about exaggeration Obs 🙄

[Bill]

I can’t think of anyone who’d need to cover their backsides once this is over Asp. Sure, with hindsight many things could have been better, even I’ve criticized some of the ideas, then again, I’m just the bloke on the street that stands back and lets others make those hard decisions.

I think I’ve said this before but if we were at the bottom of the league then it might be different but it’s just the same worldwide. At the end of the day, the only people that need to be ashamed of what they’ve done are those who deliberately broke the rules or encourage others to ignore them.

 

Bill 😊

 

[Confused52]

3 hours ago, asperity said:

I wouldn't say that it's being overstated Con, in fact I imagine that the number of people who have the virus is a multiple of those actually found to have tested positive. But we can carry on with the daily hysterical reporting of how many thousands have been tested positive (inaccurately called "cases" as if they are all at death's door), which is about 4.5% of people tested without putting it into context.

Meanwhile we have people being labelled as "covidiots" as if these are a separate set of people to those who have tested positive, presumably through no fault of their own. So if people are catching the virus, even though they are following all the rules, doesn't this show that the rules are a waste of time? Or maybe "covidiots" are somehow immune and, if they are, shouldn't we be studying them to find out if the immunity can be passed on to everyone else?

Well you are right that it is a multiple of those tested and I assume you refer to the people with symptoms being only 2/3rd of the people who are infected at any time. It isn't inaccurate to call them cases at all, people who catch a cold are cases and they aren't at deaths door either. To repeat the latest number I have seen for testing positive in Warrington is 9.8% of those tested. (While we are at it the number of cases of Flu detected in the last reported week nationally was zero).

Your second paragraph is weird. When people, occasionally including me, speak of covidiots I take it to mean those who deliberately fail to take measures to protect others. That does not imply that they have the virus because as should be plain that to keep others safe you should behave as if you have the virus and are asymptomatically infectious. That failure could be out of ignorance. carelessness or malice but it is still a deliberate failure in the case of covidiots. It is inevitable that people will catch the virus despite following the rules because the rules and guidance are to reduce the probability of infection to a lower level. Reducing it to zero is not possible because mistakes happen and people do not know who is infectious and incubation takes a long time so you do not know who gave it to you if you get it. That people get the virus despite following the rules absolutely does not show that the rules are a waste of time. Those who say that they are a waste of time have ulterior motives for saying that, possibly because they do not wish to follow some rule or other. The rules are just a set of social distancing measures to reduce the probability of infection to a manageable level to reduce consequent deaths in susceptible people. Those who advocate complete lockdown neglect the practicalities that reduction to zero is impossible without everyone on the planet having and maintaining vaccinations. The rules are a pragmatic response to reducing deaths to a lower level until at least the UK can vaccinate the susceptible, those who do not wish to achieve that aim as a joint and shared effort and actively act in ways that prevent that outcome may well be a group that might be called covidiots.

[Observer II]

Plenty of covidiots in Town today, queuing outside McDonalds; in the Market you need the foot work of Ali to keep 2m away from them .     Seem to recall when the kids were last in school, covid was rife and some schools had to close -   if you want this to go on and on, keep forcing folk together in an enclosed space.   😷

[Observer II]

Tuesday - a new record day for infections - 53,000 plus and counting .     😷

[asperity]

Con, speaking as someone who has been out of my house on average less than 2 hours a week for the last 6 months (while following the rules and more), you are preaching to the wrong person. The average person in this country is selfish and stupid, so that covers 50% of the population who don't give a monkey's what you think of them. Therefore calling selfish and stupid people covidiots is a fruitless exercise if you're trying to influence them.

[asperity]

2 hours ago, Observer II said:

Plenty of covidiots in Town today, queuing outside McDonalds; in the Market you need the foot work of Ali to keep 2m away from them .     Seem to recall when the kids were last in school, covid was rife and some schools had to close -   if you want this to go on and on, keep forcing folk together in an enclosed space.   😷

You don't have to be a covidiot to queue for a maccies, just a sheep with poor taste in food. And as I've said before if you can't keep away from people in the market or shops, then don't go in. It's your life and health and therefore your responsibility, nobody else's.

[Confused52]

1 hour ago, asperity said:

Con, speaking as someone who has been out of my house on average less than 2 hours a week for the last 6 months (while following the rules and more), you are preaching to the wrong person. The average person in this country is selfish and stupid, so that covers 50% of the population who don't give a monkey's what you think of them. Therefore calling selfish and stupid people covidiots is a fruitless exercise if you're trying to influence them.

I wish only that they not be actually encouraged in their behaviour. If they will not listen to the media they are certainly not going to listen to me. I just don't want them to think they have the equivalent of a like inadvertently from our discussions.