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[ai-geostats] Biased sampling spatial relationship

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  • Reza Nazarian
    Dear Experts To understand semivariograms in case of biased sampling, could you please explain me what is arithmetic mean of the first data points and
    Message 1 of 2 , Jun 2, 2005
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      Dear Experts
      To understand semivariograms in case of biased sampling, could you please
      explain me what is arithmetic mean of the first data points and arithmetic
      mean of the second data points within data pairs for a particular lag
      distance. ( I am reading the book: Applied Geostatistics for Reservoir
      Characterization;Mohan Kelkar...,2002,page 68)
      I need to know why they may be different. I was thinking if there are pairs
      of data, either first point of the pair or second point of the pair will be
      the same in number and if a sample could be the first point of the pair, it
      would be the second also in another place of the calculation chain and the
      mean of both first and second points in data pairs if we calculate them
      separately show the same mean because they are at the end the same???

      Please advise



      Very Best Regards
      Reza Nazarian
    • M.J. Abedini
      Reza; It might be true if you are working with regular data where the head of one pair will be the tail of the next pair. But even here the tail of the first
      Message 2 of 2 , Jun 2, 2005
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        Reza;

        It might be true if you are working with regular data where the head of
        one pair will be the tail of the next pair. But even here the tail of the
        first pair in any row or column won't correspond to any other data value.
        It is not definitely true for irregular data where there is no
        organization here.

        I would suggest to take a look at ch 4. of Isaaks and ...

        Thanks
        Abedini

        On Thu, 2 Jun 2005, Reza Nazarian wrote:

        >
        > Dear Experts
        > To understand semivariograms in case of biased sampling, could you please
        > explain me what is arithmetic mean of the first data points and arithmetic
        > mean of the second data points within data pairs for a particular lag
        > distance. ( I am reading the book: Applied Geostatistics for Reservoir
        > Characterization;Mohan Kelkar...,2002,page 68)
        > I need to know why they may be different. I was thinking if there are pairs
        > of data, either first point of the pair or second point of the pair will be
        > the same in number and if a sample could be the first point of the pair, it
        > would be the second also in another place of the calculation chain and the
        > mean of both first and second points in data pairs if we calculate them
        > separately show the same mean because they are at the end the same???
        >
        > Please advise
        >
        >
        >
        > Very Best Regards
        > Reza Nazarian
        >
        >
        >
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