Hi Isobel,
I never read your book, but in all
textbooks I have consulted so far
the kriging system is derived
in terms of covariances... then,
provided that unbiasedness conditions are
included in the system (that is ORDINARY
AND UNIVERSAL KRIGING cases) the system
is expressed in terms of semivariograms.
Instead of referring to Matheron's book,
let's look at Chiles and Delfiner's 1999
book, which should be close enough!
On page 170, second paragraph
from the bottom, I quote "There is
no variogram analog to the simple kriging
system (3.2) because then Z*-Z_0 is not
an allowable linear combination".
Next time, think twice before sending
confusing e-mails that do not help
readers who are trying to learn basic
geostat concepts!
Cheers,
Pierre
PS: If you find Matheron's work with a SIMPLE
kriging system expressed in terms of variograms,
keep it in a safe place.. it must be worth a fortune..
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On Tue, 22 May 2001, [iso-8859-1] Isobel Clark wrote:
> > In fact, once the "pseudo-sill" A cancels out from
> > the system of linear equations, the system is
> > expressed in terms of semivariograms....
> My point exactly and, if you don't do it, you don't
> make silly assumptions.
>
> > I use to think in terms of covariances since
> > it's more intuitive, and the simple kriging
> > system can only be expressed in terms of
> > covariances anyway...
> That is just so much nonsense. Ordinary kriging and
> simple kriging are derived on the basis of the
> semi-variogram and are simply slight variations on one
> another. If you don't trust my book, go back to your
> original Matheron, please.
>
> Isobel
>
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