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Rod Speed Rod Speed is offline
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Default OT: Latering thinking puzzle "Why do more peoplre die on their bithday than any other day?"



"NY" wrote in message
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"Rod Speed" wrote in message
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NY wrote
Hmm. So for statistical reasons which don't have a cause (so I'm wasting
my time looking for one!), that fact that more people are born on one
day of the year than another means the each person is more likely to die
on the anniversary of when they were born than on any other date of the
year?


Nope, the day they die is completely irrelevant. Itís the lumpiness in
the
day of the year they were born on that produces the small statistical
quirk.


The date when they die isn't irrelevant: the original question was "Why do
more people die on their birthday than any other day of [the year]". In
other words, if you plot a frequency distribution for a large population
of (birth_date - death_date) [ignoring both years] against number of
people who die on each day you get a peak around zero (birth date = death
date [ignoring both years]). This is the statistical quirk that you have
been describing. Why you suddenly say "the day they die is completely
irrelevant" baffles me and makes me wonder if goalposts have inadvertently
got moved somewhere in the discussion.


I meant that the day they die is irrelevant to the statistical quirk which
is
entirely due to the lumpiness of the day of the year everyone is born on.

I'm curious *why* it should be so,


Because of the lumpiness of the the day of the year everyone is born on.

but statistics and frequency distribution only tell us *what* happens,
with a vague suggestion that it is as a result of the varying birth rate
over a year.


Nothing vague about it, itís the reason for the statistical quirk.

I can't being to imagine *why* a varying birth rate should cause a spike
when birth date = death date,


There is no cause and effect, its just a statistical quirk.

but I'll take it on trust that it's a statistical quirk.


Given that I can't understand why it should happen, I certainly would
never have guessed that it could happen, if I hadn't already heard the
question "Why do more people die on their birthday than any other day of
[the year]", but at least now I know it does.


Maybe somewhere I'll find its cause explained in more detail that "it's a
statistical quirk" due to varying birth rate over a year.


There can be no more detail than that.

You are still mangling the day you die in with the day you were born on.


The day you die on irrelevant to the statistical quirk.


If you say that the date when you die is irrelevant to the statistical
quirk, are you sure you're still talking about original question.


Yes.

We're looking at the spike when birth date and death date are almost the
same which peaks when they are exactly the same. We can't compare birth
and death dates, to see this quirk, unless we look at death date as well
as birth date.


I wonder what the magnitude of the statistical quirk peak is, compared
with the completely separate issue that the death rate also varies over
the year (we initially assumed it was constant to keep things simple and
to avoid varying two things at once). I wonder if the variation in death
date sometimes masks the peak around birth=death date that is the
statistical quirk resulting from the varying birth rate over the year.


So maybe the annoying **** at university was right for more reasons than
that death rate varies over the year and that there are social/
accident factors which cause more death around the birthday.


Nope, the only relevant reason is that the day of the year
everyone is born on is what produces the statistical quirk.

Evidently the variation in birth rate is also significant. Maybe somehow
he deduced that a varying birth rate would cause a spike.


Realised, not deduced.

If such as deduction (in the absence of your description of the
statistical quirk) is beyond me when I'm in my 50s with A level maths and
university maths-for-engineering courses, then the fact that he worked it
out at 10 makes him a very clever (but still annoying!) **** ;-)


It has nothing to do with clever, all it needs is insight.