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Re: GEOSTATS: search radius question?

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  • Syed Abdul Rahman
    Some comments on Tom Charnock s queries: A) Generally, the rule of thumb is to limit the search neighborhood, to avoid stretching the stationarity assumption.
    Message 1 of 2 , Jun 12, 1998
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      Some comments on Tom Charnock's queries:

      A) Generally, the rule of thumb is to limit the search neighborhood,
      to avoid stretching the stationarity assumption. Of course, this is
      only fine and dandy if you have sufficient data. This could range
      from three to six wells in an offshore development to hundreds of
      thousands of points in a remote sensing problem.

      B) Consider that cross-validation can be used to fine tune
      search neighborhood parameters such as radii, points per
      quadrant, anisotropy ratios, and so forth.

      C) Limiting the number of CPU cycles can be a moot point with
      today's hardware capabilities. Also, techniques are available
      to increase computation speed, e.g. sparse matrix solvers in
      special kriging cases.

      D) Realistically speaking, 100 points is about the maximum for
      a problem involving a unique neighborhood (using all points
      instead of using a local neighborhood). Covariance matrix is
      inverted only once, and doesn't change from location to location.

      Regards,

      Syed


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