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This is by far the best explanation I have seen. Not only is this incredibly informative, it's a lesson in how to present complex(ish) facts in a way that everyone can understand.
Watch the video. Even if it's just to see how a 'scientific' video should be done! It's 7 minutes of your time that will be very well spent.
Why you can't compare Covid-19 vaccines - YouTube[^]
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Yep - 7 minutes of my time well spent.
Very well explained, doesn't sound like an advert (although at one point I thought it was drifting that way), really put across the message clearly.
Thanks for sharing
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Excellent, and very well explained. 
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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I have watched part of it but I am concerned that if 43,000 people were in the trial and that 170 tested positive, that's 0.4% of the population testing positive.
My question would be what is the false positive rate on those tests? As that is a very small proportion of the total population becoming infected and quite possibly the 170 could all be false positives.
The UK ONS refuse to answer the question False positivity rate of the COVID-19 PCR test - Office for National Statistics[^]
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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This is before I watch the video, but GuyThiebaut wrote: My question would be what is the false positive rate on those tests?
seems to leave out the obvious "what is the false negative rate".
In fact, the latter recently affected my son and his family: a friend tested positive and they were obliged to test themselves - then a retest of the positive friend and family were all negative. False alarm.
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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See my answer to Guy. Trials, I would hope, are going to be far more rigorous than testing in the real world. If Trials were based on a single PCR test, I doubt that regulators would accept the results.
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For me it's more that from a population size of 43,000 people, 0.4% of them becoming infected seems like a statistically very small proportion.
As they say the devil is in the detail and they didn't go into that very small proportion in the video - I just finished watching the whole of it.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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GuyThiebaut wrote: My question would be what is the false positive rate on those tests? As that is a very small proportion of the total population becoming infected and quite possibly the 170 could all be false positives.
I'm pretty sure that the trials would be rigorous enough to not be skewed by false positives. I've not been part of any trial, but I doubt that it relies on a single PCR test.
I don't think the ONS article, that you linked to, is related to trials. Its about the accuracy of the PCR Test in the real world. And within that article there is a link to a "Methods Article", which gives details about "Test sensitivity and specificity" - that explains their rationale on false positives. So the ONS are providing an answer - but, as you might expect with something like this, it provides a range, (85-98% accurate), rather than completely nailing it. I don't see how they could be completely accurate.
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5teveH wrote: I'm pretty sure that the trials would be rigorous enough to not be skewed by false positives.
That is how science should be done (and how I was taught to do it). Unfortunately, as science moves further from the esoteric (my world) and into the sell-able (as in medical) then, well, you can only hope.
The false-positive that sent my son & family for tests was with the "quick test", which is notoriously unreliable. The second round of testing on the source and his family was a proper test.
An important truth that, by and large, the general public is unaware of is that almost all science that manipulates real materials includes those error-bars. You do experiments, give results, and you also give information in how confident you are in the results (or, in parallel, what fraction of the sample will be transformed to the desired product - rarely 100%). Seeing only the end products, consumers live in a world of near certainty.
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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GuyThiebaut wrote:
The UK ONS refuse to answer the question False positivity rate of the COVID-19 PCR test
What?
The answer is right there in the text you linked "specificity is above 99.9%".
So, less than 0.1%
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Read that full paragraph again.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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The paragraph you got that number from.
I am replying from my mobile so I am not up for typing a whole exposition on how that paragraph is illustrating a scenario.
There is some ambiguity in the paragraph and room for interpretation:
Quote: The results show that when we consider that the sensitivity of the test could... and specificity is above 99.9%
I am reading that as "if we let the sensitivity = x and specificity be above 99.9%"
But I do see that it can also be read as "the sensitivity = x and specificity is above 99.9%"
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
modified 25-Mar-21 12:00pm.
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Well, it's admittedly not the clearest way of writing as such.
I suppose they don't want to be overly specific.
The numbers from the manufacturers are way better than that (98-99.8 sensitivity and >99.9 specificity if I recall correctly), but that's marketing.
NHS made a control study[^] together with Porton Down and Oxford, that found those numbers to be a bit lower in reality.
But again, that study is a bit old and the PCR tests are better today.
Also, to address the question you had in your original post: If someone in a trial is testing positive they are retested some days later, not only to lower the chance of false positives but also because the vaccines themselves may cause a positive test.
Apparently they don't, but they couldn't be 100% sure about that when they made the trials.
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Thanks for that information.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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Pretty good video - maybe because the final point is one I've posted a lot of times: if I'm protected from severe illness then I'm OK with it.
For one of their presentations, however, I take some exception. They present the J&J as basically being tried under more infectious conditions and that contributed to it's apparent lower efficacy. It led one, via numerous implications, that one was "comparing apples and oranges". By implication.
I suggest one think about how the efficacy is calculated: it's a relative calculation within groups of tests. A ratio. Even in less infections conditions, since it's a ratio the differences basically cancel out. It's not a factor to be completely ignored, but, the effect is really reflect in the error-bars as with absolute smaller number in both vaccine and placebo groups in tests under less infections condition. The different variants are another effect.
But, repeating myself, the final conclusion (even though the video is sort of a sales pitch to taken anything you can get - don't worry) is that prevention of a serious outcome is, indeed, the point.
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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W∴ Balboos, GHB wrote: if I'm protected from severe illness then I'm OK with it.
Yes. Me too.
W∴ Balboos, GHB wrote: For one of their presentations, however, I take some exception. They present the J&J as basically being tried under more infectious conditions and that contributed to it's apparent lower efficacy. It led one, via numerous implications, that one was "comparing apples and oranges". By implication.
I'm, sort of, with you on this. As a born sceptic, I did wonder if J&J commissioned this video! But, even if they did, its probably valid to point out that trials done at different times and in different countries, will give different results. i.e. You shouldn't make a simple comparison of trial data. You need to understand the underlying conditions.
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Every year I find Vera has done a marathon in New York strangely! (11)
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Anniversary ?
"I didn't mention the bats - he'd see them soon enough" - Hunter S Thompson - RIP
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Yay! Care to explain? You are up tomorrow either way ...
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Educated guess really, every year is an anniversary, Vera was in there along with NY - didn't bother with the marathon part.
"I didn't mention the bats - he'd see them soon enough" - Hunter S Thompson - RIP
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Every year
I find I
Vera has VERAS (Vera's)
done a marathon RAN
in New York NY
strangely! (anag)
ANNIVERSARY
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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"I didn't mention the bats - he'd see them soon enough" - Hunter S Thompson - RIP
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All the recent notebook keypads actually come with a very less "key travel". Sometimes rightly called "Chiclet" keys. You are liking this model?
I've been disliking it for so long, as I've been an fan of deep travel keys. But the new notebook I bought, I'm seeing, it takes a lot lesser effort to type. The stress on the fingers are so less.
So I'm officially joining the chiclet bandwagon. 
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I dislike the "zero travel" membrane keyboards but I am quite happy with a millimetre or two travel. And yes, a lot slicker to type on than the ASR-33 I cut my typing teeth on! I can't touch type on a touchscreen, so tablet and phone are hunt'n'peck.
Cheers,
Peter
Software rusts. Simon Stephenson, ca 1994. So does this signature. me, 2012
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