Brendan Burgess
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There is a good article in today's Irish Times by
Dr David Robert Grimes is a physicist, cancer researcher and author of The Irrational Ape: Why Flawed Logic Puts Us All at Risk and How Critical Thinking Can Save the World
Sensitivity refers to how frequently a test correctly identifies a positive result. International experience suggests that PCR-testing for Covid-19 has a sensitivity of 98 per cent,
Conversely, specificity is a measure of whether a negative result is correctly labelled. [The PCR testing has a ]specificity upwards of 99.99 per cent.
Dublin at the time of writing was averaging roughly double the national incidence of Covid-19 at 140 cases per 100,000 people.
A sensitivity of 98 per cent means that if you tested 100,000 people in Dublin, you would correctly identity 137 positive cases (98 per cent of 140),
while a specificity of 99.99 per cent means the testing would incorrectly flag a further 10 cases as positive (0.01 per cent of 100,000). This gives a “true-positive” rate’ of 137/147, or over 93 per cent.
So there are 140 cases per 100,000 in Dublin.
If we test all 100,000, 137 of these will be picked up. 3 will be given the all clear although they have Covid.
However, 10 people who do not have Covid will be told that they do have it. ( So what? They will just have to self-isolate and will be surprised at how quickly they recover.)
Brendan
Dr David Robert Grimes is a physicist, cancer researcher and author of The Irrational Ape: Why Flawed Logic Puts Us All at Risk and How Critical Thinking Can Save the World
Why there is some good news in the latest Covid-19 data
Analysis of infection rates gives reason to avoid nihilistic apathy and draw strength
www.irishtimes.com
Sensitivity refers to how frequently a test correctly identifies a positive result. International experience suggests that PCR-testing for Covid-19 has a sensitivity of 98 per cent,
Conversely, specificity is a measure of whether a negative result is correctly labelled. [The PCR testing has a ]specificity upwards of 99.99 per cent.
Dublin at the time of writing was averaging roughly double the national incidence of Covid-19 at 140 cases per 100,000 people.
A sensitivity of 98 per cent means that if you tested 100,000 people in Dublin, you would correctly identity 137 positive cases (98 per cent of 140),
while a specificity of 99.99 per cent means the testing would incorrectly flag a further 10 cases as positive (0.01 per cent of 100,000). This gives a “true-positive” rate’ of 137/147, or over 93 per cent.
So there are 140 cases per 100,000 in Dublin.
If we test all 100,000, 137 of these will be picked up. 3 will be given the all clear although they have Covid.
However, 10 people who do not have Covid will be told that they do have it. ( So what? They will just have to self-isolate and will be surprised at how quickly they recover.)
Brendan