AI-GEOSTATS: Re: Kriging, Constraints
I think there are a few things you can try before you
abandon all hope of kriging. Certainly if you have
nugget effects which are more than (say) 2/3rds of the
total sill you will get little or no validity from
using a distance weighted method such as kriging.
Possibilities you might like to look at:
(1) normalise or otherwise transform your data. Highly
skewed data, for example, will give you spurious
anisotropies and relatively high nugget effects.
(2) study the relationship with the external factors.
Perhaps you could use kriging with external drift.
Not all patterns have a distance relationship. The
semi-variogram will tell you whether this assumption
is correct, but only when calculated properly.
Calculating a semi-variogram on data which is
extremely non-Gaussian is counter productive!
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