"Rod Speed" wrote in message
...

Because there are more births on that day of the year
and so its statistically more likely that that will coincide
with the death day even if the deaths are evenly distributed
throughout the year. Which they arent in fact.

OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year. If the same number of people were born on
every date as on every other date, you're saying that the increased
probability of you dying on your birthday would not be true?

Now if the birth rate has a gradual peak at a certain time of year, more
people will be born at around that time of year. If there are more people
alive with a given birthday, does that automatically mean there there is a
greater chance that when a person dies (a fairly random event) their death
date will correspond with their birth date? And why does the probability of
any given person dying on a given date have its maximum on *exactly* the
same date as they were born - exactly as opposed to "somewhere around their
birthday".

I wonder if I will start to understand your reasoning. Am I incredibly slow
on the uptake or are you especially insightful in understanding it?

On Sat, 12 Jun 2021 21:48:44 +0100, NY wrote:
"Which leads to the rather surprising statement that, assuming you are
alive right now, you're always more likely to die today than any later
day (the probability of dying on any past day being zero, of course)."

Could you go over that bit again. I don't really follow your reasoning.
I would have thought the probability of dying on any given day will
*increase*
for each successive day, once you get past a certain age. And even
before that age-related effect kicks in, why is your chance of dying
today always greater than the chance of dying tomorrow. Is there
something that I'm not quite understanding?

OK, this is statistics so I'm probably not explaining it very well.
Assume that the probability that you die is 1%. That is, on any day,
given that you're alive at 00:00, the chance that you will still be alive
at 23:59 is 99%.

It is now 00:00 on 1st January. The probability you will die today is 1%,
as defined. If you make it to the end of the day, the probability you
will die on 2nd January is also 1%. So right now, when we don't know if
you'll survive today (the 1st) or not, the probability you will die on
2nd January is 0.99% - the probability that you will survive 1st January
(99%) times the probability that you will not survive the 2nd (1%).
Similarly the probability you will die on 3rd January is 0.9801%, that
you will die on 4th January is 0.9703% and so on.

So, if asked to bet on which day you will die, given the above I'm going
to put my money on "today". I'm probably wrong, but it's a better chance
than any other day.


You allude to neonatal mortality in your paragraph that refers to the
"zeroth birthday". Very true. But assuming you survive this "boundary
effect", won't the chance of dying stabilise to more or less the same
chance on every date, maybe with a gradual decreasing (the theory you
mention) or a gradual increasing (for elderly people) probability as
each day passes. I don't see what is special about exactly n calendar
years from your date of birth which makes the probability of death
increase on that date and decrease again after it.

That's the point - it doesn't. Assuming a newborn baby, born at 00:00 on
4th March 2021. They are more likely to die on 19th September 2050 than
on 4th March 2051. But, if I choose any arbitrary date, they are more
likely to die on that date than any of the 364 following ones. Nothing
special happens on 4th March 2022, except that I now start counting a new
year. In that year, the day they are most likely to die is the first day
of that year, which is their birthday. In every year, years beginning on
4th March, the day they are most likely to die is the first day of that
period. Add up the years, and the day of the year they're most likely to
die is 4th March.

Now, you will point out that my choice of 4th March (their birthday) to
start the year is arbitrary. I could say that in any year, starting on
21st January, the day they're most likely to die is the first day of that
year. And so if you add it up, the day they're most likely to die is 21st
January. Which is true, but... you've got a part year left over. In they
year starting 21 January 2021, the day they're most likely to die is
*not* the first day of that period, but 4th March - they can't die until
they've been born [which is another mathematical assumption that doesn't
reflect the real world]. So the extrapolation doesn't work - I add up all
the years but have an odd year left over that doesn't fit the rule, and
so can't generalize about "all years". The only way to not have an odd
part-year (where the "monotonically decreasing" rule doesn't apply) is to
choose the day of their birth as the point to start counting.
[Of course, you could point out that I still need to add in the full
years before they're born. Which is true, but that's a full year of
zeroes on every day of the year, and makes no difference to the total].

Also, in your "rather surprising statement", is that increased
probability of dying today rather than tomorrow masked by factors such a
seasonal variation in death date?

Yes. Like most mathematical problems, it is massively over-simplified.
The death rate is far from constant as it varies with age, seasons, other
conditions like wars or pandemics etc. And I'm sure this variation
massively outweighs any bias towards birthday deaths. Which is why it's
dangerous to apply simple mathematical models to the real world - there
are almost always several factors you haven't considered.

And would you expect a 10-year-old to find any of this "blindingly
obvious" to offer it as an explanation? Or anyone except a statistician
to know much about it? I *think* the guy that proposed the question was
a geographer, but I could be wrong.

No. It's far from "blindingly obvious", and I'm far from sure that this
is what the questioner was getting at. It's a rather abstract probability
model resting on some very shaky assumptions, and unless asked in the
context of a maths class I would think it's not the obvious approach to
take. I don't think you need to be a statistician, probability is taught
in some detail in school maths classes, but it's at least GCSE-level if
not A-level.

Mike

NY wrote
Rod Speed wrote

Because there are more births on that day of the year
and so its statistically more likely that that will coincide
with the death day even if the deaths are evenly distributed
throughout the year. Which they arent in fact.

OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn’t need to to get the statistical quirk.

If the same number of people were born on every date as on every other
date, you're saying that the increased probability of you dying on your
birthday would not be true?

Correct.

Now if the birth rate has a gradual peak at a certain time of year, more
people will be born at around that time of year. If there are more people
alive with a given birthday, does that automatically mean there there is a
greater chance that when a person dies (a fairly random event) their death
date will correspond with their birth date?

Like I said, ALL you need is an uneven number of births on particular days
of the year.

And why does the probability of any given person dying on a given date
have its maximum on *exactly* the same date as they were born - exactly as
opposed to "somewhere around their birthday".

I wonder if I will start to understand your reasoning.

Yeah, that will certainly be interesting to see.

Am I incredibly slow on the uptake

Not clear to me how common that problem is with basic statistics.

or are you especially insightful in understanding it?

It will be interesting to see how many others never get it.

"NY" wrote in message
...
"NY" wrote in message
...
"NY" wrote in message
...
Is there some biological property that makes a person more likely to die
n*365.25 days from their birth, for various integer values of n, than on
any other day?

Or which makes a person more likely to die on a given date because more
people were born on that date.

And extending my earlier analogy, suppose there were 10 births on every
date in January and 1 birth of each other date throughout the year.

If I was born on 1 January, why would I be more likely to die on 1 January
than on any other day in January when there were the same number of
births?

I'm assuming the deaths are independent events - that barring multi-death
disasters, the chance of me dying on a *specific* date (as opposed to
dying at around the same time of year but not necessarily on that precise
date) will not be affected by how many other people happened to be born or
happened to die on the same date - ie that my birth/death doesn't causally
affect anyone else's.

What possibly elementary mistake am I making in my reasoning?

You have missed the crucial point that the only thing that matters is that
birth day not being evenly spread thruout the year is the only thing that
matters.

Is it because their appalling spelling makes people want to hit them? Grin.
That is a joke.

Is it a bit like the clock that runs slow, statistics say that if the clock
is actually stopped, then its correct more often than the slow one is?
Brian

--

This newsgroup posting comes to you directly from...
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Blind user, so no pictures please
Note this Signature is meaningless.!
"NY" wrote in message
...
Years ago, at a party while I was at university, the conversation turned
(as it sometimes does after a lot of alcohol has been consumed) to lateral
thinking puzzles, mostly involving people dying is ways that make murder
look like suicide - or indeed suicide look like murder, and involving
people of restricted stature, failed tape recordings, piles of sawdust or
puddles of water.

One person said "More people die on their birthday than any other day. Why
is this?" This was presented as if it were a fact. We had no way of
knowing whether it was indeed the case - it was long before Wkipedia and
articles such as https://en.wikipedia.org/wiki/Birthday_effect which
describe the effect and give various medical reasons.

We tried all the obvious things like "does this include babies that are
born dead or who die within a few hours" and "does it include
alcohol-related accidents when people do stupid things at their birthday
party". No, we were told. We were over-thinking the problem and
over-complicating it. The reason was blindingly obvious. The question
became really quite smug (to the point that I could see some of my mates
were itching to punch his lights out!) and said that the teacher had asked
the question when he was a lad at school; although he'd never been asked
it before or even thought about it, he got the answer immediately. He was
amazed than none of us could work it out. "Is this true in all cultures?"
"Is it true even if you don't know the date and therefore whether today is
your birthday?" He just smiled smugly and repeated that we were thinking
far too deeply and analytically about it.

Sadly we never did find out the answer: it was left as "I'll let you think
about it. Come and tell me when you eventually work out the answer" and I
never saw him again.

Can anyone think of a logical reason, which doesn't involve
alcohol-related accidents, people who are terminally ill holding out until
their next birthday, depression/suicide "I'm a year older than I was" etc?
Something which is "blindingly obvious" even to a ten-year-old at school?

What has Giles ever done to you? Actually a friend who knows him says, he
does tend to deliberately wind people up, but is actually a kind person.

Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"NY" wrote in message
...
"GB" wrote in message
...
On 12/06/2021 14:56, NY wrote:

One person said "More people die on their birthday than any other day.
Why is this?" This was presented as if it were a fact. We had no way of
knowing whether it was indeed the case - it was long before Wkipedia and
articles such as https://en.wikipedia.org/wiki/Birthday_effect which
describe the effect and give various medical reasons.

We tried all the obvious things like "does this include babies that are
born dead or who die within a few hours" and "does it include
alcohol-related accidents when people do stupid things at their birthday
party". No, we were told. We were over-thinking the problem and
over-complicating it. The reason was blindingly obvious. The question
became really quite smug (to the point that I could see some of my mates
were itching to punch his lights out!) and said that the teacher had
asked the question when he was a lad at school; although he'd never been
asked it before or even thought about it, he got the answer immediately.
He was amazed than none of us could work it out. "Is this true in all
cultures?" "Is it true even if you don't know the date and therefore
whether today is your birthday?" He just smiled smugly and repeated that
we were thinking far too deeply and analytically about it.

Sadly we never did find out the answer: it was left as "I'll let you
think about it. Come and tell me when you eventually work out the
answer" and I never saw him again.

Can anyone think of a logical reason, which doesn't involve
alcohol-related accidents, people who are terminally ill holding out
until their next birthday, depression/suicide "I'm a year older than I
was" etc? Something which is "blindingly obvious" even to a ten-year-old
at school?


If you include deaths immediately after birth, surely that would be
enough to swing the figures?


If deaths were randomly distributed, you'd expect roughly 3 per 1000
deaths on any day of the year.

The neonatal mortality rate in this country is about 3 per 1000 live
births, with a substantial number of those on the day of birth (literally
the birthday).

So, all other things being equal, you'd have a 3 per 1000 chance of dying
on any day of the year, except your birthday when you have to add in
roughly an extra 3 per 1000 chance that you died at birth.

Sorry, but there's no tactful way of explaining that.

I agree with your explanation, But the questioner had ruled it out as
"over-complicating" the issue. He acknowledged that things like neonatal
death would have a small affect, as would psychological things like
terminal patients "holding on" to stay alive until a special event, or
people committing suicide more frequently on their birthday or at
Christmas. But all these perfectly valid effects were negligible compared
with "his" explanation - he said.

If I'd thought at the time, I'd like to have asked him whether people with
a more analytical, questioning approach would be more or less likely to
hit on "his" answer than people who thought more in terms of words and
concepts, rather than statistics and medical explanations. I'd also have
asked him whether everyone in his class worked it out at roughly the same
time: was it some thought process that had been taught at school and which
the teacher was relying on when he asked his class the question.

As an aside, the way he asked the question and responded to questions was
a textbook example of how to alienate your audience and make them want to
hit you. He had a smug attitude of "I know the answer and you don't. I'm
amazed no-one has got anywhere *near* the right answer". Think of Jeremy
Beadle crossed with Gyles Brandreth to get an idea of how insufferably
smug and gleeful he was ;-) I was reminded of the question when I saw a
reference to Gyles Brandreth the other day.

On 12/06/2021 22:58, NY wrote:
I've learned two things: firstly that he was still alive until Wednesday (I
thought he'd died a decade or so ago), and secondly that he was Maltese
rather than British.

I remember one of his books many years ago then I got thinking. One of
his "lateral thinking" examples was that we could save money and speed
up elections by getting everyone to turn on a 1KW electric fire when
prompted then measure the change in load on the grid.

Anyone can see the folly of this argument! Many would switch on a 1KW
electric fire before the prompt then turn it OFF when prompted!

Like many of his suggestions, they superficially seemed a good idea but
failed when you looked more closely at them.

On 12/06/2021 23:48, Mike Humphrey wrote:
The death rate is far from constant as it varies with age, seasons, other
conditions like wars or pandemics etc.

As someone once wrote, the death rate is always 100% whatever the
nationality, religion, ethnicity etc.

On Sun, 13 Jun 2021 09:12:59 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:



You have missed the crucial point that the only thing that matters is that
birth day not being evenly spread thruout the year is the only thing that
matters.

YOU missed the crucial point that in several countries they did NOT make any
such observation, senile wisenheimer!

--
about senile Rot Speed:
"This is like having a conversation with someone with brain damage."
MID:

"Rod Speed" wrote in message
...

It will be interesting to see how many others never get it.

As far as I remember of the postings so far to this thread, you and Mike
Humphries are the only ones who have asserted that it is true. Mike has
given a fairly rigorous explanation of probability for each successive day
after today; you have said "the variation in the birth rate over the year is
all that is needed to explain it", without explaining *why* a varying birth
rate means that there is a spike in the probability of dying exactly n
calendar years after the date when a person was born.

I can see that more people will be born on some days than others. So if you
took a sample of people, you'd expect to find more people with some
birthdays than others. But even assuming a constant death rate (ie not
varying seasonally), I don't see how that explains why person A, born at a
time of high birth rate, is more likely to die on their birthday, whereas
person B, born at a time of low birth rate, is more likely to die on their
birthday. What is so special about a period of exactly one calendar year
that makes a person more likely to die then than any other day.


What is interesting is that this statistical analysis of probability of
dying on any day, and the sudden increase on the person's birthday, isn't
mentioned in the Wikipedia article, which constrains itself to variations
due to factors that are (loosely!) within the control of the person:
accidents while celebrating, suicide as people think "I'm a year older - is
life still worth living", terminally ill people striving to stay alive until
their next birthday (or the wedding of a family member or any other
significant date).

I think I'm just going to have to accept that there *is* a reason for it
which I don't *really* understand - either because you have given an
"obviously" jump of logic from "more people are born on some days than
others" to "therefore a person is most likely to die on their birthday", or
because Mike's explanation involves summing lots of infinitesimally small
probabilities ("if I'm alive today, what's the chance I'll be alive
tomorrow; if I'm alive tomorrow, what's the chance I'll be alive the next
day" ad infinitum).

Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense. Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends. If the birth rate is peaky by calendar date and the death rate
is flat, more of the deaths will be on days which coincide with
birthdays - not because there are more deaths on those days but because
there is a greater chance that each dead person had been born on that
day.

but... if the death rate were also peaky and the peaks didn't coincide
with the peaks of the birthdays, the effect could be reduced or even
reversed. This could happen if voluntary euthanasia becomes more
widespread.


--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

On 12/06/2021 21:05, Mike Humphrey wrote:

The same applies to the year beginning on the second birthday, and each
subsequent year. Since each birthday has more deaths than the following
364 unbirthdays, when you total the deaths on each day of the year the
birthday must be the highest.


lol, cool argument.

No harm in adding a few more eggs to the pudding :-)

"Liz Tuddenham" wrote in message
id.invalid...
Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense. Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends.

If the birth rate is peaky by calendar date and the death rate
is flat, more of the deaths will be on days which coincide with
birthdays - not because there are more deaths on those days but because
there is a greater chance that each dead person had been born on that
day.

That's the bit I don't understand. *Why* will the chance that *I* die on a
given date (eg my birthday) be affected in any way whatsoever by how many
people were born on that date? Why is it more likely that I will die on a
date when many rather than few other people were born?

but... if the death rate were also peaky and the peaks didn't coincide
with the peaks of the birthdays, the effect could be reduced or even
reversed. This could happen if voluntary euthanasia becomes more
widespread.

I may be starting to understand why I'm having problems with this. (Hooray,
says Rod!)

There are two ways in which the original assertion could have been worded:

- Why do more people die on their birthday than any other day of the year?

- Why is there a greater chance that Person A (as an isolated person) will
die on his birthday than any other day of the year?

These two may or may not be identical. One considers the population as a
whole, and the other treats each person as an independent individual.

I'm really not sure what the exact wording of the question was: I've just
given the gist of it, as I remember it several decades later.

I think I'm looking at the problem from the point of view of the second
assertion (each person is an isolated, independent individual), and I don't
see how the chance of Person A dying on any day is affected in any way by
how many other people happened to have been born on that day (in one year or
another). Before all this analysis, I would have expected that the chance of
a person dying on any given date was affected solely by environmental
factors (seasonal variation in diseases, climatic variation in immune
system) etc, the person's own gradually increasing chance of dying as they
get older); and was otherwise the *same* probability of dying on any day of
the year, without a spike on the anniversary of the person's birth.

On 12/06/2021 20:06, NY wrote:
"Clive Arthur" wrote in message
...
On 12/06/2021 14:56, NY wrote:

snip

Can anyone think of a logical reason, which doesn't involve
alcohol-related accidents, people who are terminally ill holding out
until their next birthday, depression/suicide "I'm a year older than
I was" etc? Something which is "blindingly obvious" even to a
ten-year-old at school?

There are many billions of days when you didn't die before you even
had a birthday.

I tended to assume that the original question meant "that any other day
of the same year", as anything else would not make sense - and also
would tend to disprove the very assertion that he was making if you
included a denominator of (every date in the past that has ever existed).

When you die, there's something like a 1 in 365 chance of it being your
birthday. There's something like a 1 in loadsabillions chance of it not
being your birthday, because you can't have a birthday before you're born.

So the chances of you dying on your birthday are much higher than on any
other day. Of course, the chances of you dying during your lifetime are
even higher :-)

But if you take it that the question only refers to your lifetime, then,
all other things being equal, people born on 29th Feb would surely skew
the result in the opposite way to that claimed.

--
Cheers
Clive

On 13/06/2021 10:06, Liz Tuddenham wrote:
Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense. Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends. If the birth rate is peaky by calendar date and the death rate
is flat, more of the deaths will be on days which coincide with
birthdays - not because there are more deaths on those days but because
there is a greater chance that each dead person had been born on that
day.


Only if expected life is an integral value of years, which there is no
reason to expect it would be.

If expected life were say 82.5 years you would get a peak in deaths half
a year after the peak in births.

"Clive Arthur" wrote in message
...
On 12/06/2021 20:06, NY wrote:
"Clive Arthur" wrote in message
...
On 12/06/2021 14:56, NY wrote:

snip

Can anyone think of a logical reason, which doesn't involve
alcohol-related accidents, people who are terminally ill holding out
until their next birthday, depression/suicide "I'm a year older than I
was" etc? Something which is "blindingly obvious" even to a
ten-year-old at school?

There are many billions of days when you didn't die before you even had
a birthday.

I tended to assume that the original question meant "that any other day
of the same year", as anything else would not make sense - and also would
tend to disprove the very assertion that he was making if you included a
denominator of (every date in the past that has ever existed).

When you die, there's something like a 1 in 365 chance of it being your
birthday. There's something like a 1 in loadsabillions chance of it not
being your birthday, because you can't have a birthday before you're born.

So the chances of you dying on your birthday are much higher than on any
other day. Of course, the chances of you dying during your lifetime are
even higher :-)

But if you take it that the question only refers to your lifetime, then,
all other things being equal, people born on 29th Feb would surely skew
the result in the opposite way to that claimed.

Yes, I think we take it that the question is limited to your lifetime. ;-)

NY wrote
Rod Speed wrote

It will be interesting to see how many others never get it.

As far as I remember of the postings so far to this thread, you and Mike
Humphries are the only ones who have asserted that it is true.

Yes, but hardly anyone else commented at all and no one denied the original.

Mike has given a fairly rigorous explanation of probability for each
successive day after today; you have said "the variation in the birth rate
over the year is all that is needed to explain it", without explaining
*why* a varying birth rate means that there is a spike in the probability
of dying exactly n calendar years after the date when a person was born.

That’s where you keep failing to understand. It doesn’t matter when they
die day wise, the ONLY thing that matters is that some days of the year
have more BIRTHS than others. THAT’S what produces the statistical quirk.

I can see that more people will be born on some days than others. So if
you took a sample of people, you'd expect to find more people with some
birthdays than others.

And that’s why the death is irrelevant. It just more likely
that the death will occur on the same spike days.

But even assuming a constant death rate (ie not varying seasonally), I
don't see how that explains why person A, born at a time of high birth
rate, is more likely to die on their birthday, whereas person B, born at a
time of low birth rate, is more likely to die on their birthday.

That isnt what happens. Its just more likely that they will die on a spike
day.

What is so special about a period of exactly one calendar year that makes
a person more likely to die then than any other day.

Nothing, its just simple stats that spike days have more with the birth day.

What is interesting is that this statistical analysis of probability of
dying on any day, and the sudden increase on the person's birthday, isn't
mentioned in the Wikipedia article, which constrains itself to variations
due to factors that are (loosely!) within the control of the person:
accidents while celebrating, suicide as people think "I'm a year older -
is life still worth living", terminally ill people striving to stay alive
until their next birthday (or the wedding of a family member or any other
significant date).

That stuff is also relevant but isnt the reason
the obnoxious person was referring to.

I think I'm just going to have to accept that there *is* a reason for it
which I don't *really* understand

It will be interesting to see if you ever do.

- either because you have given an "obviously" jump of logic

There is no jump of logic involved, ALL that matters is
that birth days have spikes for various obvious reasons.

from "more people are born on some days than others" to "therefore a
person is most likely to die on their birthday", or because Mike's
explanation involves summing lots of infinitesimally small probabilities
("if I'm alive today, what's the chance I'll be alive tomorrow; if I'm
alive tomorrow, what's the chance I'll be alive the next day" ad
infinitum).

"Liz Tuddenham" wrote in message
id.invalid...
Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense. Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends. If the birth rate is peaky by calendar date and the death rate is
flat,
more of the deaths will be on days which coincide with birthdays - not
because there are more deaths on those days but because there is a
greater chance that each dead person had been born on that day.

Precisely.

but... if the death rate were also peaky and the peaks
didn't coincide with the peaks of the birthdays, the
effect could be reduced or even reversed.

Yes.

This could happen if voluntary euthanasia becomes more widespread.

There is already some less than random effect with death day quite
apart from the seasonal effect because presumably there is likely
to be fewer staff working on weekends when they are doing the
paperwork to decide to pull the plug on those who the relos
agree to have the plug pulled on. Not enough to cancel out
the much more profound spikes in the birth days tho.

On 13/06/2021 10:56, Pancho wrote:
On 13/06/2021 10:06, Liz Tuddenham wrote:
Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense.Â* Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends.Â* If the birth rate is peaky by calendar date and the death rate
is flat, more of the deaths will be on days which coincide with
birthdays - not because there are more deaths on those days but because
there is a greater chance that each dead person had been born on that
day.


Only if expected life is an integral value of years, which there is no
reason to expect it would be.

If expected life were say 82.5 years you would get a peak in deaths half
a year after the peak in births.


Only with a normal distribution



--
€œSome people like to travel by train because it combines the slowness of
a car with the cramped public exposure of €¨an airplane.€�

Dennis Miller

"NY" wrote in message
...
"Liz Tuddenham" wrote in message
id.invalid...
Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe
death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense. Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends.

If the birth rate is peaky by calendar date and the death rate
is flat, more of the deaths will be on days which coincide with
birthdays - not because there are more deaths on those days but because
there is a greater chance that each dead person had been born on that
day.

That's the bit I don't understand.

Yes.

*Why* will the chance that *I* die on a given date (eg my birthday) be
affected in any way whatsoever by how many people were born on that date?

It doesn’t. The ONLY thing that matters is that there birth day isnt evenly
spread.

Why is it more likely that I will die on a date when many rather than few
other people were born?

It isnt.

but... if the death rate were also peaky and the peaks didn't coincide
with the peaks of the birthdays, the effect could be reduced or even
reversed. This could happen if voluntary euthanasia becomes more
widespread.

I may be starting to understand why I'm having problems with this.
(Hooray, says Rod!)

There are two ways in which the original assertion could have been worded:

- Why do more people die on their birthday than any other day of the year?

- Why is there a greater chance that Person A (as an isolated person) will
die on his birthday than any other day of the year?

There is no difference between those except that the first sends up
up the irrelevant dead end of cause. Its an entirely statistical quirk.

These two may or may not be identical.

They are identical except in the sense that the
first one gets you off on an irrelevant side track.

One considers the population as a whole, and the other treats each person
as an independent individual.

Nope, the effect is entirely statistical.

I'm really not sure what the exact wording of the question was: I've just
given the gist of it, as I remember it several decades later.

I think I'm looking at the problem from the point of view of the second
assertion (each person is an isolated, independent individual),

Because you havent grasped that its an entirely statistical quirk.

and I don't see how the chance of Person A dying on any day is affected in
any way by how many other people happened to have been born on that day
(in one year or another).

It isnt, its entirely a statistical quirk.

Before all this analysis, I would have expected that the chance of a
person dying on any given date was affected solely by environmental
factors (seasonal variation in diseases, climatic variation in immune
system) etc, the person's own gradually increasing chance of dying as they
get older); and was otherwise the *same* probability of dying on any day
of the year, without a spike on the anniversary of the person's birth.

Not entirely, it is clear that some people do just give
up wanting to keep living and just curl up and die.

Its also quite striking how some don’t live long after retiring
and some don’t live long after the spouse dies.

"Clive Arthur" wrote in message
...
On 12/06/2021 20:06, NY wrote:
"Clive Arthur" wrote in message
...
On 12/06/2021 14:56, NY wrote:

snip

Can anyone think of a logical reason, which doesn't involve
alcohol-related accidents, people who are terminally ill holding out
until their next birthday, depression/suicide "I'm a year older than I
was" etc? Something which is "blindingly obvious" even to a
ten-year-old at school?

There are many billions of days when you didn't die before you even had
a birthday.

I tended to assume that the original question meant "that any other day
of the same year", as anything else would not make sense - and also would
tend to disprove the very assertion that he was making if you included a
denominator of (every date in the past that has ever existed).

When you die, there's something like a 1 in 365 chance of it being your
birthday. There's something like a 1 in loadsabillions chance of it not
being your birthday, because you can't have a birthday before you're born.

So the chances of you dying on your birthday are much higher than on any
other day. Of course, the chances of you dying during your lifetime are
even higher :-)

But if you take it that the question only refers to your lifetime, then,
all other things being equal, people born on 29th Feb would surely skew
the result in the opposite way to that claimed.

Yes, but that’s a much smaller factor than the spikiness in the birth days.

On 13/06/2021 11:22, The Natural Philosopher wrote:
On 13/06/2021 10:56, Pancho wrote:
On 13/06/2021 10:06, Liz Tuddenham wrote:
Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe
death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense.Â* Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends.Â* If the birth rate is peaky by calendar date and the death rate
is flat, more of the deaths will be on days which coincide with
birthdays - not because there are more deaths on those days but because
there is a greater chance that each dead person had been born on that
day.


Only if expected life is an integral value of years, which there is no
reason to expect it would be.

If expected life were say 82.5 years you would get a peak in deaths
half a year after the peak in births.


Only with a normal distribution


OK, but it is still unlikely that a skewed distribution would produce
the effect Rod was suggesting.

On 13/06/2021 08:20, Brian Gaff (Sofa) wrote:

What has Giles ever done to you? Actually a friend who knows him says, he
does tend to deliberately wind people up, but is actually a kind person.

He thinks (Thought for the Day) that petitionary prayer is just "hoping"
or "wishing" which rather misses the (religious) point.

And he refused to be drawn on whether God actually exists when
questioned on Today.

--
Max Demian

"Max Demian" wrote in message
o.uk...
On 13/06/2021 08:20, Brian Gaff (Sofa) wrote:

What has Giles ever done to you? Actually a friend who knows him says, he
does tend to deliberately wind people up, but is actually a kind person.

He thinks (Thought for the Day) that petitionary prayer is just "hoping"
or "wishing" which rather misses the (religious) point.

And he refused to be drawn on whether God actually exists when questioned
on Today.

Anyone who looks for proof that God exists and doesn't accept it as a fact
because other people think so gets a big thumbs-up from me. Religion as a
moral code for living together harmoniously makes a great deal of sense to
me; but then they go and spoil it by asking us to belief in something whose
existence can't be proved - and even make a positive *virtue* out the fact
that there is no proof. That goes against my ethos of believe nothing;
question everything; if observations don't fit the theory, maybe the theory
is wrong.

"Rod Speed" wrote in message
...
Because you havent grasped that its an entirely statistical quirk.

and I don't see how the chance of Person A dying on any day is affected
in any way by how many other people happened to have been born on that
day (in one year or another).

It isnt, its entirely a statistical quirk.

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? That
seems counter-intuitive because it is implying that the probability of any
one person dying on a given date (eg that person's birthdate) is dependent
on the number of (presumably independent *) events of other people having
been being born on that same date (though in a variety of different years).

Certainly not a conclusion I could ever have reached no matter how long I
thought about it, but if you say so, I'll have to accept (but not believe)
it ;-)

I think the main problem is that the effect is based entirely on the length
of our calendar before dates start to repeat in new year. If the universe
had been different and the earth had taken (for example) 400 days to go
round the sun (so our dates repeated every 400 rather than 365 days), then
there would still be a greater chance of someone dying 400 days (rather than
365 days) from their birth date. It seems to ascribe some significance to
one day (which relates to the periodicity of the calendar) that makes it
different from all others in the year.


(*) Maybe that's the problem: maybe they are *not* independent because the
distribution of births is based on climatic and social factors.

On Sun, 13 Jun 2021 20:31:31 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


FLUSH the trolling senile asshole's latest troll**** unread


--
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MID:

It's HILARIOUS! As always!

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"Thick pillock!"
MID:

On Sun, 13 Jun 2021 20:29:24 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the trolling senile asshole's latest troll**** unread

--
pamela about Rodent Speed:
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MID:

On Sun, 13 Jun 2021 20:17:26 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


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NY wrote
Rod Speed wrote

Because you havent grasped that its an entirely statistical quirk.

and I don't see how the chance of Person A dying on any day is affected
in any way by how many other people happened to have been born on that
day (in one year or another).

It isnt, its entirely a statistical quirk.

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. It’s the lumpiness in the
day of the year they were born on that produces the small statistical quirk.

That seems counter-intuitive because it is implying that the probability
of any one person dying on a given date (eg that person's birthdate) is
dependent on the number of (presumably independent *) events of other
people having been being born on that same date (though in a variety of
different years).

Certainly not a conclusion I could ever have reached no matter how long I
thought about it, but if you say so, I'll have to accept (but not believe)
it ;-)

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.

I think the main problem is that the effect is based entirely on the
length of our calendar before dates start to repeat in new year.

Nope.

If the universe had been different and the earth had taken (for example)
400 days to go round the sun (so our dates repeated every 400 rather than
365 days), then there would still be a greater chance of someone dying 400
days (rather than 365 days) from their birth date.

ALL that matters is the lumpiness of the birth days.

It seems to ascribe some significance to one day (which relates to the
periodicity of the calendar) that makes it different from all others in
the year.

Nope.

(*) Maybe that's the problem: maybe they are *not* independent because the
distribution of births is based on climatic and social factors.

The different lumpiness with birth days and death days is irrelevant.

On Mon, 14 Jun 2021 04:28:25 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


Nope

LOL

--
Kerr-Mudd,John addressing the auto-contradicting senile cretin:
"Auto-contradictor Rod is back! (in the KF)"
MID:

"Rod Speed" wrote in message
...
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. It’s 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'm curious *why* it should be so, 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. I can't being to imagine *why* a
varying birth rate should cause a spike when birth date = death date, 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.


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

"NY" wrote in message
...
"Rod Speed" wrote in message
...
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. It’s 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, it’s 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.

On Mon, 14 Jun 2021 09:00:11 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the trolling senile asshole's latest troll**** unread

--
Bill Wright addressing senile Ozzie cretin Rodent Speed:
"Well you make up a lot of stuff and it's total ******** most of it."
MID:

I can't be a%$ed reading through this thread to see how closely the actual wording has been
discussed - the trolls are strong here, I can see - but ISTM that you should tell it like this:

"Why is it that more people die on their birth('hidden' small pause)day than on any other?"

Don't repeat it, adopt smug expression, leave the pub with a trail of annoyance behind you...

J^n

On 13/06/2021 14:11, NY wrote:
"Max Demian" wrote in message
o.uk...
On 13/06/2021 08:20, Brian Gaff (Sofa) wrote:

What has Giles ever done to you? Actually a friend who knows him
says, he
does tend to deliberately wind people up, but is actually a kind person.

He thinks (Thought for the Day) that petitionary prayer is just
"hoping" or "wishing" which rather misses the (religious) point.

And he refused to be drawn on whether God actually exists when
questioned on Today.

Anyone who looks for proof that God exists and doesn't accept it as a
fact because other people think so gets a big thumbs-up from me.
Religion as a moral code for living together harmoniously makes a great
deal of sense to me; but then they go and spoil it by asking us to
belief in something whose existence can't be proved - and even make a
positive *virtue* out the fact that there is no proof. That goes against
my ethos of believe nothing; question everything; if observations don't
fit the theory, maybe the theory is wrong.

The key is that a Christian behaves *as if* a God existed, that is what
is called 'faith',

Those who believe that he actually does, are just a bit intellectually
challenged.



--
"First, find out who are the people you can not criticise. They are your
oppressors."
- George Orwell