3 ms·

Okay - I'm going to reveal my statistics ignorance here - but if they did get a false positive, how does 0.0% fall within the range of possibilities (or is that

Okay - I'm going to reveal my statistics ignorance here - but if they did get a false positive, how does 0.0% fall within the range of possibilities (or is that allowing for it might be 0.0499..% or lower?)

samatman 6y ago
All of the sibling answers are correct, but ignoring another possibility: that the timeline is simply wrong, and SARS2 was present in the US early enough that the "false positive" is in fact a true positive. Which can't lead to a "true 0%", since there's no such animal. But it could mean that all of the tests gave correct answers, in the trial.
- squnch 6y ago
  They could be testing this on five year old samples.
  - MarkusQ 6y ago
    From the article: > Specificity samples were derived from de-identified excess serum specimens sent to our clinical virology laboratory in 2018 and 2019. So...not five years ago, and it is even possible that a significant number were from late 2019.
richardwhiuk 6y ago
Rounding - 0.000000001% is treated as 0.0%. (More likely, 0.04% or similar is being treated as 0.0%, but I haven't done the maths to confirm what the number would be)
IfOnlyYouKnew 6y ago
Not ignorant at all... I believe the issue is that the statement ("95% confidence interval of 0.0 to 0.5") has just slightly different/counterintuitive meaning in this case. In general, you can always make the interval larger, but you want it to be smaller. With the understanding that the 95% is a lower bound, [0.0, 25%] is also a valid confidence interval. But, yes, you are entirely correct as to the practical meaning. 0% itself is impossible, but 0.0...1% could still happen.
renewiltord 6y ago
What is the smallest number greater than 0? For the things considered here, the point 0 is measure zero so open starting at 0 and closed at 0 are the same. L
barbegal 6y ago
Correct, I rounded to the appropriate number of significant figures. I hate extra significant figures which suggest that the data is more precise than it really is
madhadron 6y ago
We know that 0% isn't a real value for a test's error rate, but the statistical procedure being used doesn't have any "look, it's never zero" criteria built into its math. All it says is that 0 is one of the numbers consistent with the data given these criteria.

samatman 6y ago

All of the sibling answers are correct, but ignoring another possibility: that the timeline is simply wrong, and SARS2 was present in the US early enough that the "false positive" is in fact a true positive. Which can't lead to a "true 0%", since there's no such animal. But it could mean that all of the tests gave correct answers, in the trial.

squnch 6y ago
They could be testing this on five year old samples.
- MarkusQ 6y ago
  From the article: > Specificity samples were derived from de-identified excess serum specimens sent to our clinical virology laboratory in 2018 and 2019. So...not five years ago, and it is even possible that a significant number were from late 2019.

richardwhiuk 6y ago

Rounding - 0.000000001% is treated as 0.0%. (More likely, 0.04% or similar is being treated as 0.0%, but I haven't done the maths to confirm what the number would be)

IfOnlyYouKnew 6y ago

Not ignorant at all... I believe the issue is that the statement ("95% confidence interval of 0.0 to 0.5") has just slightly different/counterintuitive meaning in this case. In general, you can always make the interval larger, but you want it to be smaller. With the understanding that the 95% is a lower bound, [0.0, 25%] is also a valid confidence interval. But, yes, you are entirely correct as to the practical meaning. 0% itself is impossible, but 0.0...1% could still happen.

renewiltord 6y ago

What is the smallest number greater than 0? For the things considered here, the point 0 is measure zero so open starting at 0 and closed at 0 are the same. L

barbegal 6y ago

Correct, I rounded to the appropriate number of significant figures. I hate extra significant figures which suggest that the data is more precise than it really is

madhadron 6y ago

We know that 0% isn't a real value for a test's error rate, but the statistical procedure being used doesn't have any "look, it's never zero" criteria built into its math. All it says is that 0 is one of the numbers consistent with the data given these criteria.