Not a phd,
Tom
Enrique Diaz-Alvarez wrote:
> DANIEL.DAVIES at flemings.com wrote:
>
> > >e iSadly, I didn't mean anything so clever. Among finance/econ geeks, E is
> >
> > also the "expectation" operator. So E(0) in this context is "Expectation
> > at time 0". Brad said that life expectancy at birth was the least worst
> > measure. I objected that E(0) wasn't equal to E(0)(E(10)) "expectation at
> > time 0 of expectation at time 10". Usually, this would be equal to E(0) -
> > after all, there's something funny about expecting your expectation to
> > change, which is where the reference to "law of iterated expectations" came
> > in. But when you're talking about life expectancies, you can expect that
> > if you survive until ten, then your expectation of your lifespan will
> > change markedly. I suggested that you should be comparing expectancies on
> > the basis of life expectancy at the most common age for people to die,
> > which, frankly, sounds a lot less silly when you use five-shilling words
> > like "modal"
>
> I am still confused.
>
> 1) What's the difference between E(10) and E(0)(E(10))? Don't they both
> represent "how long people who make it to age 10 are expected to live"?
>
> 2) If 1) is true, then E(0) can never be equal to E(0)(E(10)), unless noone
> dies before age 10, right?
>
> 3) Wouldn't the modal age of death be tremendously dependent on the interval
> you choose to distribute deaths? If you do it by month, then you'll get that
> the modal "month" of death is the one after birth. If you do it by decade,
> then you'd probably get the 80s (I am just guessing here). If so, then
> choosing E(modal age of death) doesn't make much sense, does it?
>
> --
>
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