[ExI] Impressive book: Farewell to Alms

[Samantha Atkins]

On Feb 4, 2008, at 8:22 PM, hkhenson wrote:

> At 12:16 PM 2/4/2008, BillK wrote:
>> On Feb 4, 2008 4:54 PM, hkhenson wrote:
>
> snip
>
>> There just aren't enough wills compared with the population numbers.
>> People who wrote wills are a small, self-selected subset of the
>> population. It is a great leap to conclude that the small subset of
>> wills is representative of the whole population. The vast majority of
>> the population had lives that never got into the records anywhere.
>
> Elemental sampling theory treats numbers as large
> as the population as effectively infinite.  The
> statistical error you get out of samples is such
> that a sample of a few hundred gives decent
> expected error bounds on the whole
> population.  If it's a leap of faith the Gallop polls make the same  
> leap.
>
> Do you agree with Clark's numbers for the will
> data he had?  If you do, what reason do you have
> to expect the results *not* to apply to the population as a whole?

Elementary sampling theory requires that the sample is random over the  
population.  The objection was that those who wrote wills in those  
times were not randomly representative of the population as a whole.   
A random sample of wills may say a fair amount about the subset of the  
population who had a need and interest in writing a will while saying  
very little conclusive about the population as a whole.   Getting a  
good random sample of the population of interest is not a leap of  
faith.  Some care needs to be exercised and a reasonable case made for  
having satisfied this requirement before any statistical argument  
based on such a sample has much merit.

>

- samantha