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AI-GEOSTATS: Re: Kriging, Constraints

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  • Isobel Clark
    Ursula 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
    Message 1 of 2 , Oct 13, 2003
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      Ursula

      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!

      Isobel
      http://geoecosse.bizland.com/whatsnew.htm

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