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Re: GEOSTATS: Impact on kriging variance ?

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  • Hagues
    Dear all, Gregoire posted a question regarding using a limited number of points to make estimations in order to take more local effects into account . I am
    Message 1 of 2 , Apr 11 5:44 AM
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      Dear all,

      Gregoire posted a question regarding using a "limited number of points to
      make estimations in order to take more local effects into account".

      I am not too sure if this response is relevant but there was a study
      presented by Danie Krige (1997) which looked at the problem of trying to
      reduce the inherent smoothing of kriging by reducing the number of data
      points used to derive an estimate.

      The process of reducing the number of data points to derive an estimate
      resulted in conditional biases in the results. Danie's conclusions were
      that to avoid conditional biases one had to use a suitable number of points
      to derive the estimates, but at the same time accept the unavoidable fact
      that the resultant estimates will always be accompanied by some smoothing.

      Reference

      KRIGE, D.G.; 1997: Block kriging and the fallacy of endeavouring to reduce
      or eliminate smoothing. Proceedings of the 2nd Regional APCOM Symposium on
      Computer Applications and Operations Research in the Minerals industries,
      Moscow.

      Hope this helps.

      Richard Hague


      -----Original Message-----
      From: Gregoire Dubois <gregoire.dubois@...>
      To: ai-geostats@... <ai-geostats@...>
      Date: Thursday, 6 July 2000 6:31
      Subject: GEOSTATS: Impact on kriging variance ?


      >Dear all,
      >
      >I posted two months ago a question for which I didn't
      >receive any answer. Was the answer too obvious or my
      >question stupid ? Here is a second try.
      >
      >A common practice in geostatistics is to use only
      >a limited number of points to make the estimations
      >in order to take more local effects into account. However,
      >the modeling of the semivariogram is made on the
      >whole data set. My question is: what is the impact
      >of the use of a limited number of points on the kriging
      >variance (which should be affected by such a procedure) ?
      >Any references ?
      >
      >I will summarize
      >
      >Best regards
      >
      >Gregoire
      >
      >
      >Gregoire Dubois
      >Section of Earth Sciences
      >Institute of Mineralogy and Petrography
      >University of Lausanne
      >Switzerland
      >
      >Currently detached in Italy
      >
      >http://curie.ei.jrc.it/ai-geostats.htm
      >
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