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Re: AI-GEOSTATS: Negative variances

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  • Isobel Clark
    Kevin There is something badly wrong with your software. With ordinary kriging, it is not possible to get negative variances. With lognormal kriging, it is not
    Message 1 of 2 , Nov 2, 2001
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      Kevin

      There is something badly wrong with your software.

      With ordinary kriging, it is not possible to get
      negative variances.

      With lognormal kriging, it is not possible to get
      negative varianse or negative estimates unless you are
      using a large additive constant.

      Isobel Clark
      http://uk.geocities.com/drisobelclark

      --- Kevin Lowe Rfn <KLowe@...> wrote: > Hi
      all
      >
      > I have been experimenting with various kriging
      > methods in estimating
      > Witwatersrand gold grades (South Africa) using
      > Datamine software. I found
      > that using lognormal ordinary kriging has resulted
      > in negative variances in
      > some blocks.
      >
      > My question is why does this happen and what is the
      > significance of it?
      >
      > Kevin Lowe
      > e-mail KLowe@...
      >
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