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GEOSTATS: K. Malakhanov's question

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  • Donald Myers
    One must be a little careful, kriging is not a unique interpolation method hence to say that one is going to compare kriging with IWD does not make sense
    Message 1 of 1 , May 21, 1997
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      One must be a little careful, kriging is not a unique
      interpolation method hence to say that one is going to
      compare "kriging" with "IWD" does not make sense

      First of all, is the mean treated as constant or a polynomial
      (if the latter what terms are included, i.e., universal
      kriging). Even if the mean is considered constant is it
      considered known or unknown (simple vs ordinary kriging).
      What variogram/covariance model(s) are used, what parameters
      (including possible anisotropies). Is a unique neighborhood
      used or a moving neighborhood, if the latter what conditions
      are placed on it (radii, minimum/maximum number of points,
      sectors, # of empty sectors?).

      Note that the thin plate spline is a special case, i.e.,
      a particular covariance.

      Even IWD can vary, see Kane et al (Computers and Geosciences
      1982) on an empirical study of the effect of the exponent.

      To construct the contour map one must first interpolate onto
      a regular grid, the choice of the grid mesh for interpolation
      will have some effect.

      Are point values interpolated or block values (one might
      use either for contouring)?

      What is the ultimate use of the contouring? That will have
      some bearing on how to judge the comparison.

      Finally the comparison will be valid only for the specific
      data set and does in general not imply anything about
      the comparison for a different data set.

      Wanting to compare different possible results is an
      interesting/useful question but it will not have a
      definitive answer.

      Donald E. Meyrs
      Donald E. Myers
      Department of Mathematics
      University of Arizona
      Tucson, AZ 85721
      http://www.u.arizona.edu/~donaldm
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