On Thu, 9 Dec 2004, Digby Millikan wrote:

> Meng-Ying,

>

> Even if your population variance and sill do not match identically,

> the sample sill should still be a better estimate than the sample

variance,

> when you consider the amount of clustering which occurs in sampling.

>

> Digby

>

All right, if you think the clustering of data values (I'm not talking

about clustering of locations) are not be part of the representation of

population.

I just found an example that I can use as population, with 2500 points

and it's 2-D (in the GSLIB manual, second realization of SGSIM.OUT-- if

you happen to have this data set) and found the sill and variance of this

population not matching (sill~20, variance=18.63).

I intended to use a smaller sample so everyone can have fun playing the

data (even if you use M$-Excel to calculate the variogram), which also

speaks out more what I'd like to say. But seems like people are more

interested in discussing the size of population. . . I'll leave it here

then, if nobody found any problem estimating population variance using the

sill value. Maybe I'm just psychologically not comfortable estimating

variance like that. . . (I'll probably follow you people if I found no

theoretic derivation for my thinking.)

It's fun discussing with you people though, and I'm happy to have this

much discussion for my debut.

Meng-ying