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GEOSTATS: Kriging paradox

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  • Richard Gaze
    Dear geostatisticians and the like, Have any of you encountered the problem that can sometimes arise when kriging with strings of data (eg contiguous
    Message 1 of 3 , Aug 19 11:19 PM
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      Dear geostatisticians and the like,


      Have any of you encountered the problem that can sometimes arise when kriging with strings of data (eg contiguous composites along drill holes) where you get ludicrously large weights assigned to the samples at the ends of the string?

      This problem is documented beautifully by Robert F. Shurtz in his papers

      'Propagation of Error and Paradox in Geostatistics'

      'The geostatistics machine and the drill core paradox'

      I would like to hear your thoughts on this and suggested solutions. Some 'quick fixes' have been proposed to deal with this paradox, but they most certainly do not solve the problem. It's the kriging system itself which is at fault.


      Regards

      Richard Gaze
      Geostatistician
      MRT Perth WA




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    • Ali_Alaa@seo.state.nm.us
      Dear Richard, This is unfortunately one of the shortcomings of Kriging. Ali and Lall have developed series of nonparametric techniques that address many of
      Message 2 of 3 , Aug 20 8:44 AM
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        Dear Richard,
        This is unfortunately one of the shortcomings of Kriging. Ali and Lall
        have developed series of nonparametric techniques that address many of
        these shortcomings such as 1) data clustering, 2) stationarity
        assumption, and 3) Variogram identification.

        We specifically address the problem you are inquiring in one of our
        papers:

        Ali, A. I., and Lall, U., "A Kernel Estimator for Stochastic subsurface
        characterization from drill log data", Ground Water, 34, 4, 647, 1996.

        If you have any question, please feel free to contact me; or professor
        Lall at:
        ulall@...

        Alaa
        _________________________________________________________
        Alaa I. Ali, Ph.D., P.E.
        Senior Engineer
        Groundwater/Geostatistics/Geotechnical specialist
        New Mexico State Engineer Office
        e-mails: aali@...; or aali@...
        http://www.engineering.usu.edu/Departments/cee/faculty/ulall/
        Phone: 505-827-6125 Fax: 505-827-6188
        _________________________________________________________

        > Dear geostatisticians and the like,
        >
        >
        > Have any of you encountered the problem that can sometimes arise when
        kriging wi
        > th strings of data (eg contiguous composites along drill holes) where
        you get lu
        > dicrously large weights assigned to the samples at the ends of the
        string?
        >
        > This problem is documented beautifully by Robert F. Shurtz in his
        papers
        >
        > 'Propagation of Error and Paradox in Geostatistics'
        >
        > 'The geostatistics machine and the drill core paradox'
        >
        > I would like to hear your thoughts on this and suggested solutions.
        Some 'quick
        > fixes' have been proposed to deal with this paradox, but they most
        certainly do
        > not solve the problem. It's the kriging system itself which is at
        fault.
        >
        >
        > Regards
        >
        > Richard Gaze
        > Geostatistician
        > MRT Perth WA
        >
        >
        >
        >
        > --
        > *To post a message to the list, send it to ai-geostats@....
        > *As a general service to list users, please remember to post a summary
        > of any useful responses to your questions.
        > *To unsubscribe, send email to majordomo@... with no subject
        and
        > "unsubscribe ai-geostats" in the message body.
        > DO NOT SEND Subscribe/Unsubscribe requests to the list!
        >

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      • Ph. Latour
        Further to the message sent by Richard Gaze the 20 August 1997 regarding the Kriging paradox, I would be interested by more details and comments on this
        Message 3 of 3 , Aug 21 1:54 PM
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          Further to the message sent by Richard Gaze the 20 August 1997 regarding
          the
          Kriging paradox, I would be interested by more details and comments on this
          subject (e.g. the paper from Robert F. Shurtz).
          If someone could please send me information, I would appreciate it greatly.
          ========================================================
          Philippe Latour Latour Consulting
          Tel : (+33) (0)298 305 587/516 32 rue des Primeveres
          Fax : (+33) (0)298 305 587 29480 Le Relecq-Kerhuon
          E-mail: philippe.latour@... France
          ========================================================
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