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Re: AI-GEOSTATS: Re: Urgent help needed: Power-law Semi-variogram Range

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  • Edzer J. Pebesma
    Joseph, not all spatial processes have correlation lengths; some processes show an increase in variance whenever you increase the domain. Think of (1D case)
    Message 1 of 2 , Feb 12, 2004
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      Joseph,

      not all spatial processes have correlation lengths; some
      processes show an increase in variance whenever you
      increase the domain. Think of (1D case) Brownian
      motion. Power law variograms result from processes
      that have no correlation length; IIRC, Brownian
      motion has a linear variogram (power=1) with no sill.
      --
      Edzer

      Joseph Oyeyele wrote:

      >Thank you for your reply,
      >
      >By the transect method, I mean by taking a straight line through the field of observation. The transect method computes the variogram along this line only, since it is an isotropic process generated from a functional form.
      >
      >Is there a reliable method for determining the range(correlation length).
      >I wrote a function in Matlab to determine and plot the variogram. I cross-checked by running the generated data through GSTAT --- it also results in a power law variogram.
      >
      >Please advise on the best approach to determine the correlation length in this case.
      >
      >Thanks
      >
      >Joseph.
      >
      >
      >


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