More California

wrote:
On Aug 24, 10:49 am, Dan Connelly
wrote:
If I assume this rate is time-independent,

y = integral(0 to infinity) age * f'(age) d age

Which obviously differs from the life expectancy of someone born at any moment of
time, including today.

You assumed this rate is time-independent.

But your math is, of course, correct. We distinguish between a cohort
life expectancy and a period life expectancy and the context is
generally so clear that we don't specify it. When we write "the life
expectancy at birth in 2000" and "life expectancy at birth in 2001"
we're talking about period rates. When we write "the life expectancy
at birth for the cohort of 1857" we're talking about the cohort rate.

It's sort of like the convention for saying "life expectancy" instead
of "life expectancy at birth." Notice in your equation "integral(0 to
infinity)". If you took integral(X to infinity) that would be
expectation of life at age X, conditional on having survived to age X.
That's why I referred to life expectancy as a conditional expected
value.

Your partial derivative is the hazard rate. Your p(t,t0)dt is the
survivorship function. Life expectancy calculations are the same as
MTBF calculations. Your issue is congruent with what are called
censored observations.

Okay, now we're aligned.


I think we went over this a couple of years ago.


I think we did....

writes:

On Aug 23, 2:27 pm, I wrote:
On Aug 23, 2:10 pm, Dan Connelly wrote:

From:http://en.wikipedia.org/wiki/Life_expectancy

Oh dear. I'll have to edit that when I get a chance.

Last night I asked more than 1% of the world's PhD demographers to
rate the section of the Wikipedia entry that Dan cited for content and
accuracy. The average rating was a just a bit higher than 6 out of 10.

Was it a randomly chosen sample of slightly more than 1% of the
world's Ph.D. demographers?

If not, then surely those same demographers can tell you that their
opinions don't necessarily reflect those of the other 99%.

In article . com,
wrote:

On Aug 23, 2:27 pm, I wrote:
On Aug 23, 2:10 pm, Dan Connelly wrote:

From:http://en.wikipedia.org/wiki/Life_expectancy

Oh dear. I'll have to edit that when I get a chance.

Last night I asked more than 1% of the world's PhD demographers to
rate the section of the Wikipedia entry that Dan cited for content and
accuracy. The average rating was a just a bit higher than 6 out of 10.

I recently learned that sample size is much more important than sample
proportion. 60% sounds like a fairly good mark.

--
Ryan Cousineau http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

On Aug 24, 2:09 pm, Ryan Cousineau wrote:

Last night I asked more than 1% of the world's PhD demographers to
rate the section of the Wikipedia entry that Dan cited for content and
accuracy. The average rating was a just a bit higher than 6 out of 10.

I recently learned that sample size is much more important than sample
proportion. 60% sounds like a fairly good mark.

We agreed 6 out of 10 is a D.

You're right about sample size, but my dining room table is only so
big.

On Aug 24, 2:06 pm, Doug Anderson
wrote:

Was it a randomly chosen sample of slightly more than 1% of the
world's Ph.D. demographers?

Hell no.

If not, then surely those same demographers can tell you that their
opinions don't necessarily reflect those of the other 99%.

That's surely true. We disproportionately represent the PhD
demographers who train other demographers.

writes:

On Aug 24, 2:06 pm, Doug Anderson
wrote:

Was it a randomly chosen sample of slightly more than 1% of the
world's Ph.D. demographers?

Hell no.

If not, then surely those same demographers can tell you that their
opinions don't necessarily reflect those of the other 99%.

That's surely true. We disproportionately represent the PhD
demographers who train other demographers.

That's unlikely to be the _only_ bias in your sample!

wrote:
Last night I asked more than 1% of the world's PhD demographers to
rate the section of the Wikipedia entry that Dan cited for content and
accuracy. The average rating was a just a bit higher than 6 out of 10.

As dumbasses go, you're one in a billion. Approximately.

Bob Schwartz

On Aug 24, 3:17 pm, Bob Schwartz
wrote:

As dumbasses go, you're one in a billion. Approximately.

http://groups.google.com/group/rec.b...3260cec15a69a3

On Aug 24, 3:29 pm, wrote:
On Aug 24, 3:17 pm, Bob Schwartz
wrote:

As dumbasses go, you're one in a billion. Approximately.

http://groups.google.com/group/rec.b...3260cec15a69a3


Please. Enough with the boasting about your 6000 girlfriends,
5 in the Bay Area alone.

On Aug 24, 3:45 pm, "
wrote:

Please. Enough with the boasting about your 6000 girlfriends,
5 in the Bay Area alone.

http://www.canoe.ca/BasketballChambe...ct13_wil2.html