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600Re: AI-GEOSTATS: variogram at zero ( gamma(0) ) in the kriging

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  • Isobel Clark
    Apr 28, 2002
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      Jack

      There is a schism in the geostatistical community
      between those who do and those who don't make gamma(0)
      equal to 0.

      Some people argue that the nugget effect is 'sampling
      error' and that gamma(0) should equal c0 so that
      kriging does not honour the data values. It also makes
      your kriging variances smaller (emphasis).

      I (personally) find it a bit weird to have smaller
      supposed errors if you do not trust your data.

      Software packages differ as to whether they do or do
      not go to zero. Simplest way to check is to replace
      your nugget effect by a spherical component with a
      very short range of influence and see if your answers
      change.

      Isobel Clark
      http://geoecosse.bizland.com/pg2000.htm

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