• what is false positive?

    From RichD@21:1/5 to All on Tue Aug 18 15:44:34 2020
    A schoolboy question:

    Thinking about the COVID issue, I haven't seen any data
    on false positive/negative rates on the tests.

    But first, a definition of 5% false pos.:

    i) Given 100 positive results, it means 5 are erroneous?
    or,
    ii) Given 100 subjects non-infected, it means 5 will return positive?

    You could translate these to the predictions for an individual.
    Odd, that I never thought about this before -

    And why is it, in medical testing generally, they focus
    on the false positive rate, but discount false negatives?

    --
    Rich

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Rich Ulrich@21:1/5 to r_delaney2001@yahoo.com on Wed Aug 19 01:58:59 2020
    On Tue, 18 Aug 2020 15:44:34 -0700 (PDT), RichD
    <r_delaney2001@yahoo.com> wrote:

    A schoolboy question:

    Thinking about the COVID issue, I haven't seen any data
    on false positive/negative rates on the tests.

    Test + Test -
    True + A B
    True - C D

    A = True Positive
    B = False Negative
    C = False Positive
    D = True Negative


    But first, a definition of 5% false pos.:

    i) Given 100 positive results, it means 5 are erroneous?

    C / (C+A) ? no

    or,
    ii) Given 100 subjects non-infected, it means 5 will return positive?

    C / (C+D) ? yes

    A quick Google gives the definition,
    "The false positive rate is the proportion of all negatives that still
    yield positive test outcomes"

    "Sensitivity" and (negative) "specificty" are the terms used
    more often in epidemiology papers, to comprise the errors
    in both directions, Together, they define the reliability of
    the test. Technical papers will always discuss BOTH since
    most of the tests have a quantitative cutoff that can be
    adjusted, whereby you increase either at the expense of
    the other.

    The cutoff that is used will sometimes take into acount the
    base-rate of the disease, since a change in base rate will
    change the actual number and rate of errors in a particular
    sample.


    You could translate these to the predictions for an individual.
    Odd, that I never thought about this before -

    And why is it, in medical testing generally, they focus
    on the false positive rate, but discount false negatives?

    Your phrase - "in medical testing generally" - does not describe
    the reality of medical testing. It may describe what you have
    been reading, lately, in newspapers about covid-19.

    Below are links to some sources of articles that include some
    on sensitivity and specificity concerns. This content was originally
    posted here by David Jones on June 1, 2020, under Subj:
    "Analyzing Covid Data"



    <<
    I have not tried to follow any of the above. But, anyone with a
    statistical interest in this epidemic should probably know about the
    following list of articles associtaed with the Significance magazine:

    https://www.significancemagazine.com/business/647

    The list features the UK rather heavily and relates to the RSS
    Covid-19
    Task Force, which is outlined here:

    https://rss.org.uk/news-publication/news-publications/2020/general-news/rss-launches-new-covid-19-task-force/

    and:

    https://rss.org.uk/policy-campaigns/policy/covid-19-task-force/

    There is some overlap in these lists.


    --
    Rich Ulrich

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From David Jones@21:1/5 to Rich Ulrich on Wed Aug 19 06:43:31 2020
    Rich Ulrich wrote:

    On Tue, 18 Aug 2020 15:44:34 -0700 (PDT), RichD
    <r_delaney2001@yahoo.com> wrote:

    A schoolboy question:

    Thinking about the COVID issue, I haven't seen any data
    on false positive/negative rates on the tests.

    Test + Test -
    True + A B
    True - C D

    A = True Positive
    B = False Negative
    C = False Positive
    D = True Negative


    But first, a definition of 5% false pos.:

    i) Given 100 positive results, it means 5 are erroneous?

    C / (C+A) ? no

    or,
    ii) Given 100 subjects non-infected, it means 5 will return
    positive?

    C / (C+D) ? yes

    A quick Google gives the definition,
    "The false positive rate is the proportion of all negatives that still
    yield positive test outcomes"

    "Sensitivity" and (negative) "specificty" are the terms used
    more often in epidemiology papers, to comprise the errors
    in both directions, Together, they define the reliability of
    the test. Technical papers will always discuss BOTH since
    most of the tests have a quantitative cutoff that can be
    adjusted, whereby you increase either at the expense of
    the other.

    The cutoff that is used will sometimes take into acount the
    base-rate of the disease, since a change in base rate will
    change the actual number and rate of errors in a particular
    sample.


    You could translate these to the predictions for an individual.
    Odd, that I never thought about this before -

    And why is it, in medical testing generally, they focus
    on the false positive rate, but discount false negatives?

    Your phrase - "in medical testing generally" - does not describe
    the reality of medical testing. It may describe what you have
    been reading, lately, in newspapers about covid-19.

    Below are links to some sources of articles that include some
    on sensitivity and specificity concerns. This content was originally
    posted here by David Jones on June 1, 2020, under Subj:
    "Analyzing Covid Data"



    <<
    I have not tried to follow any of the above. But, anyone with a
    statistical interest in this epidemic should probably know about the following list of articles associtaed with the Significance magazine:

    https://www.significancemagazine.com/business/647

    The list features the UK rather heavily and relates to the RSS
    Covid-19
    Task Force, which is outlined here:


    https://rss.org.uk/news-publication/news-publications/2020/general-news/rss-launches-new-covid-19-task-force/

    and:

    https://rss.org.uk/policy-campaigns/policy/covid-19-task-force/

    There is some overlap in these lists.


    For a quick look at some actual numbers regarding test accuracy, see https://www.finddx.org/covid-19/sarscov2-eval-molecular/molecular-eval-results/

    ... this also shows the large number of different tests available and
    indicates how well the test accuracies are known

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Bruce Weaver@21:1/5 to RichD on Wed Aug 19 07:33:42 2020
    On Tuesday, August 18, 2020 at 6:44:37 PM UTC-4, RichD wrote:
    A schoolboy question:

    Thinking about the COVID issue, I haven't seen any data
    on false positive/negative rates on the tests.

    But first, a definition of 5% false pos.:

    i) Given 100 positive results, it means 5 are erroneous?
    or,
    ii) Given 100 subjects non-infected, it means 5 will return positive?

    You could translate these to the predictions for an individual.
    Odd, that I never thought about this before -

    And why is it, in medical testing generally, they focus
    on the false positive rate, but discount false negatives?

    --
    Rich

    Hi Rich. Here is a BMJ article & infographic that might help:

    https://www.bmj.com/content/369/bmj.m1808

    Notice that it unlike the example Rich Ulrich showed, it puts the Test results in the rows (T+ and T-) and the true disease status in the columns (D+ and D-). Using this approach, Rich's table would be recast as follows:

    D+ D-
    T+ tp fp
    T- fn tn

    Or using a-d:

    D+ D-
    T+ a b
    T- c d

    With this layout, the usual calculations are:

    Sens = TPF = p(T+|D+) = a / (a+c)
    Spec = TNF = p(T-|D-) = d / (b+d)
    PPV (or PV+) = p(D+|T+) = a / (a+b)
    NPV (or PV-) = p(D-|T-) = d / (c+d)
    FPF = p(T+|D-) = b / (b+d) = 1 - Spec
    FNF = p(T-|D+) = c / (a+c) = 1 - Spec

    The final F in TPF, TNF FPF and FNF stands for "fraction". Sometimes you see "rate" in place of fraction, but it really is a fraction (or proportion).

    Novices (and I'm not suggesting you are one!) often find it easier if this is just expressed in terms of row and column percentages. For the layout I have shown above:

    Column % for a = Sens (or TPF)
    Column % for d = Spec (or TNF)
    Column % for b = 1-Spec = FPF
    Column % for c = 1-Sens = FNF

    Row % for a = PV+ (or PPV) -- predictive value of a positive test
    Row % for d = PV- (or NPV) -- predictive value of a negative test
    Row % for b = 1-PV+
    Row % for c = 1-PV-


    Getting back to your question:

    i) Given 100 positive results, it means 5 are erroneous?

    This is describing the row percentage for cell b in the table above, so is equal to 1 - PV+.


    or,
    ii) Given 100 subjects non-infected, it means 5 will return positive?

    This is describing the column percentage for cell b, which is equal to 1-Spec or the FNF.

    As I said, this is the *conventional* terminology regarding false positive and false negative fractions (or rates). But who knows for sure whether journalists are following these conventions!

    HTH.

    PS- In case it is not obvious, Sens is short for sensitivity and Spec for specificity.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Rich Ulrich@21:1/5 to dajhawkxx@nowherel.com on Thu Aug 20 15:36:21 2020
    On Wed, 19 Aug 2020 06:43:31 +0000 (UTC), "David Jones" <dajhawkxx@nowherel.com> wrote:



    For a quick look at some actual numbers regarding test accuracy, see >https://www.finddx.org/covid-19/sarscov2-eval-molecular/molecular-eval-results/

    ... this also shows the large number of different tests available and >indicates how well the test accuracies are known

    Thanks -
    A few comments -

    That says it is updated on July 3, so there are more tests
    available by now, I'm sure.

    Those are high values for both sensitivity and specificity,
    many of them measured for their samples at 100%.

    First, I am surprised and impressed. The numbers I
    saw (probably in June) for a couple of tests were lower.
    Those high numbers give me more reason to trust that
    recent re-analysis of older data (mostly from April) where
    they concluded that the "actual number" of cases ranged
    from twice to 13 times (varying by place) the number of
    "confirmed diagnoses".

    Second, those were for "clean" samples. Collection in
    the field introduces errors and inaccuracy. For instance,
    the "deep nasal swab" is uncomfortably deep, and can
    be done wrong, failing to get a good sample (ergo, lower
    sensitivity).

    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    --
    Rich Ulrich

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From David Jones@21:1/5 to Rich Ulrich on Thu Aug 20 22:37:10 2020
    Rich Ulrich wrote:

    On Wed, 19 Aug 2020 06:43:31 +0000 (UTC), "David Jones" <dajhawkxx@nowherel.com> wrote:



    For a quick look at some actual numbers regarding test accuracy, see

    https://www.finddx.org/covid-19/sarscov2-eval-molecular/molecular-eval-results/

    ... this also shows the large number of different tests available
    and indicates how well the test accuracies are known

    Thanks -
    A few comments -

    That says it is updated on July 3, so there are more tests
    available by now, I'm sure.

    Those are high values for both sensitivity and specificity,
    many of them measured for their samples at 100%.

    First, I am surprised and impressed. The numbers I
    saw (probably in June) for a couple of tests were lower.
    Those high numbers give me more reason to trust that
    recent re-analysis of older data (mostly from April) where
    they concluded that the "actual number" of cases ranged
    from twice to 13 times (varying by place) the number of
    "confirmed diagnoses".

    Second, those were for "clean" samples. Collection in
    the field introduces errors and inaccuracy. For instance,
    the "deep nasal swab" is uncomfortably deep, and can
    be done wrong, failing to get a good sample (ergo, lower
    sensitivity).

    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    Yes, this earlier article https://www.significancemagazine.com/science/667-comparing-and-assessing-covid-19-tests
    quotes some rather lower success rates for tests.

    The high succces rates quoted seem to relate to this statemen:t
    "On 19 February 2020, FIND launched an expression of interest (EOI) for
    test developers of in vitro diagnostics (IVDs) that detect SARS-CoV-2
    nucleic acid (molecular tests). The EOI closed on 9 March 2020. Over
    200 submissions were received and applications were reviewed ..." Out
    of which the 21 "best" were selected for independent evaluation and
    inclusion in the tables: https://www.finddx.org/covid-19/sarscov2-eval-molecular/
    ... so the tables only include tests available early on.

    A wider view might be found on this page: https://finddx.shinyapps.io/COVID19DxData/
    which eventually provides a graphical scatter plot of Sensitivity
    against Specificity, subject to various options ... but it does take
    some time for the graph to appear, so some patience is needed. I don't
    really unbderstand what is going on here, but you might want to move
    the top button from "Antibody" to "Molecular".

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Rich Ulrich@21:1/5 to dajhawk18xx@@nowhere.com on Sat Aug 22 01:42:44 2020
    On Thu, 20 Aug 2020 22:37:10 +0000 (UTC), "David Jones" <dajhawk18xx@@nowhere.com> wrote:

    Rich Ulrich wrote:

    On Wed, 19 Aug 2020 06:43:31 +0000 (UTC), "David Jones"
    <dajhawkxx@nowherel.com> wrote:



    For a quick look at some actual numbers regarding test accuracy, see
    https://www.finddx.org/covid-19/sarscov2-eval-molecular/molecular-eval-results/

    ... this also shows the large number of different tests available
    and indicates how well the test accuracies are known

    Thanks -
    A few comments -

    That says it is updated on July 3, so there are more tests
    available by now, I'm sure.

    Those are high values for both sensitivity and specificity,
    many of them measured for their samples at 100%.

    First, I am surprised and impressed. The numbers I
    saw (probably in June) for a couple of tests were lower.
    Those high numbers give me more reason to trust that
    recent re-analysis of older data (mostly from April) where
    they concluded that the "actual number" of cases ranged
    from twice to 13 times (varying by place) the number of
    "confirmed diagnoses".

    Second, those were for "clean" samples. Collection in
    the field introduces errors and inaccuracy. For instance,
    the "deep nasal swab" is uncomfortably deep, and can
    be done wrong, failing to get a good sample (ergo, lower
    sensitivity).

    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    Yes, this earlier article >https://www.significancemagazine.com/science/667-comparing-and-assessing-covid-19-tests
    quotes some rather lower success rates for tests.

    The high succces rates quoted seem to relate to this statemen:t
    "On 19 February 2020, FIND launched an expression of interest (EOI) for
    test developers of in vitro diagnostics (IVDs) that detect SARS-CoV-2
    nucleic acid (molecular tests). The EOI closed on 9 March 2020. Over
    200 submissions were received and applications were reviewed ..." Out
    of which the 21 "best" were selected for independent evaluation and
    inclusion in the tables: >https://www.finddx.org/covid-19/sarscov2-eval-molecular/
    ... so the tables only include tests available early on.

    A wider view might be found on this page: >https://finddx.shinyapps.io/COVID19DxData/
    which eventually provides a graphical scatter plot of Sensitivity
    against Specificity, subject to various options ... but it does take
    some time for the graph to appear, so some patience is needed. I don't
    really unbderstand what is going on here, but you might want to move
    the top button from "Antibody" to "Molecular".

    I think - antibody is whether you might have long-term immunity;
    molecular is the virus by PCR; antigen is the virus otherwise (?).

    I thoroughly did not understand "heat map."

    The page was last updated today, so this one may be worth
    checking for changes across the weeks.

    I read today that Penn State is considering using a scratch-and-
    sniff test -- The article said that casual reports get 50% of cases
    reporting on total loss of sense of smell as an /early/ symptom,
    and it may be 75% that admit to it on being pressed. That is
    good sensitivity for a very simple, immediate, and cheap test.
    Reusable, too, for everyone nearby?

    The usual coronavirus case does /not/ have nasal congestion -
    common cold could be the source of most false positives, but
    the loss of smell is more severe for covid-19.

    --
    Rich Ulrich

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From David Jones@21:1/5 to Rich Ulrich on Thu Sep 10 19:21:34 2020
    Rich Ulrich wrote:


    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    This article ...

    https://news.sky.com/story/coronavirus-what-are-the-different-types-of-covid-19-tests-12068081

    outlines some of the different tests that might be available. Once
    again, it is UK-centric.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From David Jones@21:1/5 to Rich Ulrich on Tue Sep 15 22:52:34 2020
    Rich Ulrich wrote:

    On Wed, 19 Aug 2020 06:43:31 +0000 (UTC), "David Jones" <dajhawkxx@nowherel.com> wrote:



    For a quick look at some actual numbers regarding test accuracy, see

    https://www.finddx.org/covid-19/sarscov2-eval-molecular/molecular-eval-results/

    ... this also shows the large number of different tests available
    and indicates how well the test accuracies are known

    Thanks -
    A few comments -

    That says it is updated on July 3, so there are more tests
    available by now, I'm sure.

    Those are high values for both sensitivity and specificity,
    many of them measured for their samples at 100%.

    First, I am surprised and impressed. The numbers I
    saw (probably in June) for a couple of tests were lower.
    Those high numbers give me more reason to trust that
    recent re-analysis of older data (mostly from April) where
    they concluded that the "actual number" of cases ranged
    from twice to 13 times (varying by place) the number of
    "confirmed diagnoses".

    Second, those were for "clean" samples. Collection in
    the field introduces errors and inaccuracy. For instance,
    the "deep nasal swab" is uncomfortably deep, and can
    be done wrong, failing to get a good sample (ergo, lower
    sensitivity).

    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    THis letter from the RSS to a newspaper (September 11) https://rss.org.uk/RSS/media/File-library/News/Press%20release/Letter-to-the-Times-on-government-moonshot-testing-plans-110920.pdf
    suggests that the tests currently being used for those who might have
    the infection are rather poor for certain intended uses.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Rich Ulrich@21:1/5 to dajhawk18xx@@nowhere.com on Wed Sep 16 00:36:27 2020
    On Tue, 15 Sep 2020 22:52:34 +0000 (UTC), "David Jones" <dajhawk18xx@@nowhere.com> wrote:

    Rich Ulrich wrote:

    On Wed, 19 Aug 2020 06:43:31 +0000 (UTC), "David Jones"
    <dajhawkxx@nowherel.com> wrote:



    For a quick look at some actual numbers regarding test accuracy, see
    https://www.finddx.org/covid-19/sarscov2-eval-molecular/molecular-eval-results/

    ... this also shows the large number of different tests available
    and indicates how well the test accuracies are known

    Thanks -
    A few comments -

    That says it is updated on July 3, so there are more tests
    available by now, I'm sure.

    Those are high values for both sensitivity and specificity,
    many of them measured for their samples at 100%.

    First, I am surprised and impressed. The numbers I
    saw (probably in June) for a couple of tests were lower.
    Those high numbers give me more reason to trust that
    recent re-analysis of older data (mostly from April) where
    they concluded that the "actual number" of cases ranged
    from twice to 13 times (varying by place) the number of
    "confirmed diagnoses".

    Second, those were for "clean" samples. Collection in
    the field introduces errors and inaccuracy. For instance,
    the "deep nasal swab" is uncomfortably deep, and can
    be done wrong, failing to get a good sample (ergo, lower
    sensitivity).

    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    THis letter from the RSS to a newspaper (September 11) >https://rss.org.uk/RSS/media/File-library/News/Press%20release/Letter-to-the-Times-on-government-moonshot-testing-plans-110920.pdf
    suggests that the tests currently being used for those who might have
    the infection are rather poor for certain intended uses.

    Thanks. I suspect that the same holds for most testing in the US,
    but it is worth "discussion" - as the author says - about what
    everyone is talking about as "the current tests" and the alternatives.
    Do positive test resuts (somewhere) get re-tested with more precision?
    I believe they were doing that at the NFL training camps, because
    I did hear of a couple of false positives from their testing -- they
    could not have decided that if they did not do the retest.

    article -
    << Tests cause harm when they miss or wrongly diagnose cases.
    Our current tests have 1 and 2% false positive rates – which, when
    millions are being tested every day, risks causing personal and
    economic harm to tens of thousands of people. This problem is
    exacerbated if the new tests, as is likely, are less accurate than the
    ones used currently.
    If mass-testing can give people confidence that they are
    disease-free, tests need to detect nearly all cases. Our current tests
    miss around a fifth of those with the disease – if the new tests are
    even less sensitive, they may not be accurate enough for the safe
    running of events but could be useful for complementing social
    distancing measures. >>

    --
    Rich Ulrich

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From David Jones@21:1/5 to Rich Ulrich on Mon Sep 21 11:22:09 2020
    Rich Ulrich wrote:

    On Tue, 15 Sep 2020 22:52:34 +0000 (UTC), "David Jones" <dajhawk18xx@@nowhere.com> wrote:

    Rich Ulrich wrote:

    On Wed, 19 Aug 2020 06:43:31 +0000 (UTC), "David Jones"
    <dajhawkxx@nowherel.com> wrote:



    For a quick look at some actual numbers regarding test accuracy,
    see >> >

    https://www.finddx.org/covid-19/sarscov2-eval-molecular/molecular-eval-results/

    ... this also shows the large number of different tests available
    and indicates how well the test accuracies are known

    Thanks -
    A few comments -

    That says it is updated on July 3, so there are more tests
    available by now, I'm sure.

    Those are high values for both sensitivity and specificity,
    many of them measured for their samples at 100%.

    First, I am surprised and impressed. The numbers I
    saw (probably in June) for a couple of tests were lower.
    Those high numbers give me more reason to trust that
    recent re-analysis of older data (mostly from April) where
    they concluded that the "actual number" of cases ranged
    from twice to 13 times (varying by place) the number of
    "confirmed diagnoses".

    Second, those were for "clean" samples. Collection in
    the field introduces errors and inaccuracy. For instance,
    the "deep nasal swab" is uncomfortably deep, and can
    be done wrong, failing to get a good sample (ergo, lower
    sensitivity).

    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    THis letter from the RSS to a newspaper (September 11)

    https://rss.org.uk/RSS/media/File-library/News/Press%20release/Letter-to-the-Times-on-government-moonshot-testing-plans-110920.pdf
    suggests that the tests currently being used for those who might
    have the infection are rather poor for certain intended uses.

    Thanks. I suspect that the same holds for most testing in the US,
    but it is worth "discussion" - as the author says - about what
    everyone is talking about as "the current tests" and the alternatives.
    Do positive test resuts (somewhere) get re-tested with more precision?
    I believe they were doing that at the NFL training camps, because
    I did hear of a couple of false positives from their testing -- they
    could not have decided that if they did not do the retest.

    article -
    << Tests cause harm when they miss or wrongly diagnose cases.
    Our current tests have 1 and 2% false positive rates – which, when
    millions are being tested every day, risks causing personal and
    economic harm to tens of thousands of people. This problem is
    exacerbated if the new tests, as is likely, are less accurate than the
    ones used currently.
    If mass-testing can give people confidence that they are
    disease-free, tests need to detect nearly all cases. Our current tests
    miss around a fifth of those with the disease – if the new tests are
    even less sensitive, they may not be accurate enough for the safe
    running of events but could be useful for complementing social
    distancing measures. >>

    Back to pool testing ... a recent BBC radio programme on pool testing
    can be accessed here (9 minutes long): https://www.bbc.co.uk/sounds/play/p08rwy4n

    --- SoupGate-Win32 v1.05
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  • From Rich Ulrich@21:1/5 to dajhawk18xx@@nowhere.com on Thu Sep 24 02:36:11 2020
    On Thu, 10 Sep 2020 19:21:34 +0000 (UTC), "David Jones" <dajhawk18xx@@nowhere.com> wrote:

    Rich Ulrich wrote:


    One of the developments I have seen hyped in the last
    week or so is the potential for a cheap saliva-test that may
    be administered at home, with quick results. The lack of
    ideal sensitivity is offset by cheap-and-quick. I think I read
    that the US government is paying about $100 per test, though
    I don't know how much of that goes to the labs.

    This article ...

    https://news.sky.com/story/coronavirus-what-are-the-different-types-of-covid-19-tests-12068081

    outlines some of the different tests that might be available. Once
    again, it is UK-centric.

    Stephen Colbert (late night comic) passed along the news
    item that the Finns have trained dogs to detect the
    coronavirus. I see several news stories available. The dogs
    are being tried at an airport terminal, for incoming passengers.

    This one repeats what Colbert said, that the dogs can
    detect the virus potentially a day or two earlier than
    PCP tests. It also says "94.5% accuracy" - which
    I hope means sensitivity.

    https://www.newsweek.com/dog-smell-coronavirus-covid-testing-pcr-nose-swab-finland-helsinki-1533905

    This one also says "94% accuracy", also without being clear
    on the criterion. It adds comments about the logistics of dogs
    being used for this. To work in the airport, they have to
    tolerate the noisy environment.

    https://www.nytimes.com/2020/09/23/world/europe/finland-dogs-airport-coronavirus.html

    --
    Rich Ulrich

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