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[ai-geostats] A question on conditional simulations

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  • Abhijith Titus D'souza
    Hello List: First of all I would like to thank all of you for your feedback on my earlier question. Just as an exercise I conducted conditional simulation on
    Message 1 of 2 , Nov 14, 2005
      Hello List:

      First of all I would like to thank all of you for your
      feedback on my earlier question.

      Just as an exercise I conducted conditional simulation
      on my dataset. I used the turning bands algorithm
      method and the sequential gaussian method. While the
      turning bands method produced a similar map as
      compared to IDW and kriging, sequential gaussian
      produced an interesting map. It matched the estimation
      maps from IDW and kriging only in those neighborhoods
      which contained the sample values. For neighborhoods
      containing no sample values it tended to overestimate,
      i.e as one went away from the sample values the SG
      method overestimated while the estimation maps did
      not.The maps were the average of 100 realizations.I
      was wondering if someone could tell me why this
      happens. I am still trying to figure out the theory
      behind the simulation methods, but it seems too far
      fetched for me.

      Thanks
      Abhijith



      __________________________________
      Yahoo! FareChase: Search multiple travel sites in one click.
      http://farechase.yahoo.com
    • Isobel Clark
      How many simulations did you do? Isobel Abhijith Titus D souza wrote: Hello List: First of all I would like to thank all of you for
      Message 2 of 2 , Nov 15, 2005
        How many simulations did you do?
        Isobel

        Abhijith Titus D'souza <abhijitidz_4@...> wrote:
        Hello List:

        First of all I would like to thank all of you for your
        feedback on my earlier question.

        Just as an exercise I conducted conditional simulation
        on my dataset. I used the turning bands algorithm
        method and the sequential gaussian method. While the
        turning bands method produced a similar map as
        compared to IDW and kriging, sequential gaussian
        produced an interesting map. It matched the estimation
        maps from IDW and kriging only in those neighborhoods
        which contained the sample values. For neighborhoods
        containing no sample values it tended to overestimate,
        i.e as one went away from the sample values the SG
        method overestimated while the estimation maps did
        not.The maps were the average of 100 realizations.I
        was wondering if someone could tell me why this
        happens. I am still trying to figure out the theory
        behind the simulation methods, but it seems too far
        fetched for me.

        Thanks
        Abhijith



        __________________________________
        Yahoo! FareChase: Search multiple travel sites in one click.
        http://farechase.yahoo.com

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