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GEOSTATS: spatial correlation method

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  • Ionut Aron
    Hi all, I am very new to spatial statistics and I have the following problem: I have an Arc/INFO coverage with two roads: one is from the existing road network
    Message 1 of 2 , Oct 31, 2000
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      Hi all,

      I am very new to spatial statistics and I have the following problem:
      I have an Arc/INFO coverage with two roads: one is from the existing road
      network and the other one is the same road modelled with a road modelling
      software.
      How can I assess the spatial correlation between these two representations
      of the same road ?

      Thank you,

      Ionut

      Ionut Aron, MF Candidate
      Forest Resources Management
      Forest Sciences Centre
      2045-2424 Main Mall
      University of British Columbia
      Vancouver, BC., Canada V6T 1Z4
      Telephone: (604) 822-4148



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    • Isobel Clark
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      Message 2 of 2 , Nov 1, 2000
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        > How can I assess the spatial correlation between
        > these two representations
        > of the same road ?

        If your information has the same spatial co-ordinates
        in both sets, you can produce a co-located cross
        semi-variogram by simply calculating the covariance
        for each lag:

        (g_i - g_j)(f_i - f_j)

        where g and f are the two variables, i and j are two
        locations a specified distance apart. Average over all
        pairs the same distance apart and divide by two. This
        is exactly analogous to calculating the covariance
        between the two at that specified distance:

        (g_i - gbar)(f_j - fbar)

        only you don't need the two means. If your samples are
        not at the same locations you need the non-co-located
        semi-variogram, referred to by some authors as a
        "pseudo cross semi-variogram" and given as standard in
        Noel Cressie's book. The basic form of this is

        (g_i - f_j)^2

        notation as above. This assumes that the two variables
        have the same mean or have been standardised somehow.

        Kriging is always the same. Watch out for Volume 2 of
        Practical Geostatistics -- PG2001. Lots of
        explanations there.

        Isobel Clark
        drisobelclark@...
        http://uk.geocities.com/drisobelclark
        Isobel Clark



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