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GEOSTATS: cokriging in gslib

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  • Inge Frette
    Hello folks, not being an expert in geostatistics I wonder why the power model of the variogram model in Gslib is not allowed for when doing cokriging ? Anyone
    Message 1 of 4 , Dec 13, 1999
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      Hello folks,
      not being an expert in geostatistics I wonder why the power model of the
      variogram model
      in Gslib is not allowed for when doing cokriging ?

      Anyone that knows why ?

      Regards from Inge Frette


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      GEOLOGICA AS Phone : +47 51 87 58 15 (from 1.1.2000)
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    • Pierre Goovaerts
      Hello, Power models are not allowed for SIMPLE cokriging in the current version of cokb3d although they are allowed for simple kriging. Note that simple
      Message 2 of 4 , Dec 13, 1999
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        Hello,

        Power models are not allowed for SIMPLE cokriging
        in the current version of cokb3d although they
        are allowed for simple kriging.
        Note that simple (co)kriging systems need to be expressed in
        terms of covariances but pseudo-variances can be used
        to convert unbounded semivariograms into covariances.

        My advice is: Do not use simple cokriging since the
        assumptions of stationarity of the means are rarely met.
        Use the option ordinary cokriging and compare the
        two options: traditional and standardized cokriging since
        the unbiasedness constraints can influence the quality
        of the predictions, e.g. see
        Goovaerts, P. 1998. Ordinary cokriging revisited.
        Mathematical Geology, 30(1):21--42.

        Cheers,

        Pierre
        <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

        ________ ________
        | \ / | Pierre Goovaerts
        |_ \ / _| Assistant professor
        __|________\/________|__ Dept of Civil & Environmental Engineering
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        On Mon, 13 Dec 1999, Inge Frette wrote:

        > Hello folks,
        > not being an expert in geostatistics I wonder why the power model of the
        > variogram model
        > in Gslib is not allowed for when doing cokriging ?
        >
        > Anyone that knows why ?
        >
        > Regards from Inge Frette
        >
        >
        > ************************************************************************
        > Inge Frette Phone : +47 51 87 54 50
        > GEOLOGICA AS Phone : +47 51 87 58 15 (from 1.1.2000)
        > P.O.Box 8034 Fax : +47 51 87 52 87
        > N-4003 STAVANGER E-mail: inge.frette@...
        > NORWAY Web : http://www.geologica.no
        > ************************************************************************
        >
        > --
        > *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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