• #### extrapolating Maria's death toll

From Rich Ulrich@21:1/5 to All on Mon Jun 4 12:14:11 2018
The original, "official" death toll in Puerto Rico from Hurricane
Maria was 64 - those were directly attributed.

"Excess deaths" in 42 days after from September 20, 2017,
came to 1052. There are a few other estimates, using different
methods and different time frames.

https://www.nytimes.com/2018/06/02/us/puerto-rico-death-tolls.html

What has been in the news in the past week is a point
estimate of 4645 deaths. That is based on a survey of 3000
randomly selected households. Those households described
38 deaths of members of the extended family. Using whatever
demographic information information they had available, the
surveyors extrapolated that to obtain a confidence interval
of approximately (800, 8500) for the number of total deaths.
The reported number, 4645, is the midpoint of the 95% CI.

So - There is an estimate of 4645 deaths, extrapolated from
an observed count of 38 deaths.

What surprises me, a bit, is that the estimate is repeated so
often as if it were a firm number; and no one points to the
error range.

I suppose that once you get into complications like the error
range, you also might be pushed to discuss why the whole
esimate is apt to be biased to the low end - which is also
complicated.

The same author, Sheri Fink, also had a May 30th article

--
Rich Ulrich

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• From Stan Brown@21:1/5 to Rich Ulrich on Mon Jun 4 20:04:45 2018
On Mon, 04 Jun 2018 12:14:11 -0400, Rich Ulrich wrote:
the
surveyors extrapolated that to obtain a confidence interval
of approximately (800, 8500) for the number of total deaths.
The reported number, 4645, is the midpoint of the 95% CI.

So - There is an estimate of 4645 deaths, extrapolated from
an observed count of 38 deaths.

What surprises me, a bit, is that the estimate is repeated so
often as if it were a firm number; and no one points to the
error range.

It doesn't surprise me. I always insisted that my students report
intervals, not midpoint ± error, and for exactly this reason.

(In this case, the midpoint is 4650 not 4645; was that a typo, or a
mistake from another source?)

What we don't know (at least I don't) is whether, in this case, the
interval 800-8000 was given to the media and they computed or
miscomputed the midpoint, or 4650±3850 was given to the newspapers,
and they dropped the ±3850.

--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://BrownMath.com/
Shikata ga nai...

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• From Rich Ulrich@21:1/5 to the_stan_brown@fastmail.fm on Tue Jun 5 00:40:19 2018
On Mon, 4 Jun 2018 20:04:45 -0400, Stan Brown
<the_stan_brown@fastmail.fm> wrote:

On Mon, 04 Jun 2018 12:14:11 -0400, Rich Ulrich wrote:
the
surveyors extrapolated that to obtain a confidence interval
of approximately (800, 8500) for the number of total deaths.
The reported number, 4645, is the midpoint of the 95% CI.

So - There is an estimate of 4645 deaths, extrapolated from
an observed count of 38 deaths.

What surprises me, a bit, is that the estimate is repeated so
often as if it were a firm number; and no one points to the
error range.

It doesn't surprise me. I always insisted that my students report
intervals, not midpoint Â± error, and for exactly this reason.

(In this case, the midpoint is 4650 not 4645; was that a typo, or a
mistake from another source?)

What we don't know (at least I don't) is whether, in this case, the
interval 800-8000 was given to the media and they computed or
miscomputed the midpoint, or 4650Â±3850 was given to the newspapers,
and they dropped the Â±3850.

See the article - I took the "approximate" description of the CI
to mean that numbers were rounded (a) for convenience or
(b) to avoid the implication of more precision than the numbers
deserve. And 4645 would be rounded from the original point-estimate.

I'm glad to see your comment. Now I think I see the source
of something that was bothering me --

I presume that the media worked from a press release, and
the scientists got the coverage they intended. The "official"
number of 64 was irresponsible, or, it is irresponsible to leave
it hanging out there as if it were meaningful. There are several
estimates of a bit over 1000 deaths, for a shorter period. And
there were over 900 cremations with no report of causes of death.

I think that the folks publishing in the New England Journal
of Medicine were willing to over-emphasize the "4645" in a press
release because, given all the other information, the whole range
is set lower than it ought to be. So, they won't be shown to be
grossly over the right figure, if better news comes out. And they
thought that there was public value in being "impressive" rather
than being more technically precise.

- This is part of the awkward interface between science and
the public assimilation of science.

--
Rich Ulrich

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