1281GEOSTATS: modeling the variogram
- Jun 10, 1999Hi all,
I have some question concerning the modeling.
I have calculated different variogram estimators.
The traditional semivariogram reveals spatial continuity. But the
shape, the ranges and anisotropies are better estimated by the more
robust pairwise relative semivariogram.
My questions are:
(1) Could I model the experimental pairwise relative semivariogram
(or other more robust variograms) or does it affect the
kriging estimator and it's estimation variance considering the
accuracy? And if yes do I have to standardize the sill to one?
(2) Is there a difference between modeling the traditional
semivariogram with it's original sill value and with a sill
standardized to one.
(3) What is really necessary to yield the correct estimates? Only the
ratios of nugget and sill structures and their corresponding ranges
or the real values provided by the traditional semivariogram with a
non standardized sill?
Goovaerts 1997 ("Geostatistics for natural resources estimation")
warns against using the more robust estimators as substitutes for
the traditional semivariogram. But for example Srivastava and Parker
1989 ("Robust measures of spatial continuity") did model several
robust estimators besides the traditional semivariogram.
If a robust measure provides a better spatial continuity I would say
that I can use it for modeling. Only the estimation variance will be
affected and should not be taken as an absolute value but used in
relative terms to compare the variances.
Thanks in advance
Department of Soil Science
The University of Trier
address: Engelstr.104, 54292 Trier, Germany
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