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AI-GEOSTATS: Extensive variances

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  • Ruben Roa Ureta
    Hi group: Thanks for the replies about coordinate transformation near the poles (that was some time ago but i went on a research cruise for 2 weeks and
    Message 1 of 1 , Mar 3, 2004
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      Hi group:
      Thanks for the replies about coordinate transformation near the poles
      (that was some time ago but i went on a research cruise for 2 weeks and
      couldn't reply in a timely manner). I gathered UTM is fine. Carmen Hervada
      enlightened me by pointing out that variogram modelling requires metric
      distance units and that was the main reason for the UTM transformation
      from latitude-longitude.
      In the book Mining Geostatistics by Journel and Huijbregts there are
      charts of extensive variances, which i used to compute estimation
      variances for totals after kriging (the formula was the corresponding
      extensive variance times the sill times the number of elementary sampling
      units times the area covered by each sampling unit, IIRC). There were
      different charts depending on the geometry of the sampling and the model
      variogram. My copy of the book was lost and it is out of print in Amazon.
      Does anyone know of a website where the same charts can be read? Or are
      there charts in the FORTRAN codes of the GSLIB library? Thanks for your
      help.
      Ruben

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