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AI-GEOSTATS: Moran's I calculation and appropriate use.

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  • Raechel Waters
    Dear All, I had a couple of questions regarding the calculation and use of Moran s I. Firstly, does anyone know of free software or routines that will
    Message 1 of 4 , Aug 7, 2001
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      Dear All,

      I had a couple of questions regarding the calculation and use of Moran's I.

      Firstly, does anyone know of free software or routines that will calculate
      Moran's I (for user defined lags) and provide a significance value for the
      calculated statistic? I have played with Crimestat (thank you Dr Levine)
      and GS+ but neither of these programs does both of the above, or atleast
      not in my explorations of the routines - please correct me if I am
      wrong. If there is not freeware available what alternatives would you
      recommend?

      Secondly, does anyone have comment on using such a statistic on a small (49
      point) data set. The data values are arranged in a 7x7 grid and are point
      measures of a continuous field. I am using the statistic to determine the
      spatial extent of autocorrelation as a first attempt to determine the
      spatial organisation of the distributions. I am however rather new to
      this field and so not fully versed in the limitations or potential pitfalls
      of such statistics. Moran's I was not recommended to me in an original
      query I posted regard this spatial statistics for small data sets. I am
      wondering if there are reasons why.

      Thank you again for you help.

      Raechel Waters



      `````````````````````````````````````````````````````
      Marine Biology
      School of Biology
      Flinders University
      GPO Box 2100
      Adelaide
      SA 5001

      Phone: 08 8201 5234
      Fax: 08 8201 3015
      Mobile: 0401 304 106


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    • Raechel Waters
      Dear All, I had a couple of questions regarding the calculation and use of Moran s I. Firstly, does anyone know of free software or routines that will
      Message 2 of 4 , Aug 7, 2001
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        Dear All,

        I had a couple of questions regarding the calculation and use of Moran's I.

        Firstly, does anyone know of free software or routines that will calculate
        Moran's I (for user defined lags) and provide a significance value for the
        calculated statistic? I have played with Crimestat (thank you Dr Levine)
        and GS+ but neither of these programs does both of the above, or atleast
        not in my explorations of the routines - please correct me if I am
        wrong. If there is not freeware available what alternatives would you
        recommend?

        Secondly, does anyone have comment on using such a statistic on a small (49
        point) data set. The data values are arranged in a 7x7 grid and are point
        measures of a continuous field. I am using the statistic to determine the
        spatial extent of autocorrelation as a first attempt to determine the
        spatial organisation of the distributions. I am however rather new to
        this field and so not fully versed in the limitations or potential pitfalls
        of such statistics. Moran's I was not recommended to me in an original
        query I posted regard this spatial statistics for small data sets. I am
        wondering if there are reasons why.

        Thank you again for you help.

        Raechel Waters



        `````````````````````````````````````````````````````
        Marine Biology
        School of Biology
        Flinders University
        GPO Box 2100
        Adelaide
        SA 5001

        Phone: 08 8201 5234
        Fax: 08 8201 3015
        Mobile: 0401 304 106


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        * As a general service to the users, please remember to post a summary of any useful responses to your questions.
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      • Ramesh Krishnamurthy
        dear all, i have developed a logistic regression model to predict the spatial distribution of three Himalayan pheasants (that i have studied) viz. western
        Message 3 of 4 , Aug 8, 2001
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          dear all,
          i have developed a logistic regression model to
          predict the spatial distribution of three Himalayan
          pheasants (that i have studied) viz. western tragopan,
          himalayan monal and koklass. i now want to improve the
          model by including the effect of spatial
          autocorrelation found in the predicted probability. i
          am trying calculate the autocovariate based on the
          method suggested by Augustine et.al. published in
          J.Applied Ecology. i am not clear about how does
          iteration help in calculating the autocovariate and
          how to decide on the optimum iteration required for
          the data set. i would greatly appreciate if any one on
          the list would educate me or suggest me the study
          material on the subject.

          regards

          ramesh


          =====


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        • Nicholas Lewin-Koh
          Hi Ramesh, You haven t given us a lot to go on. I assume you mean auto-logistic regression. There have been several threads on this in the last few months so
          Message 4 of 4 , Aug 8, 2001
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            Hi Ramesh,
            You haven't given us a lot to go on. I assume you mean auto-logistic
            regression. There have been several threads on this in the last few months
            so check the AI-geostats archives.

            I am not sure what you mean by iteration, what is being iterated? It might
            also help if you told us a little more about your sampling design and the
            nature of the data.

            Nicholas

            On Wed, 8 Aug 2001, [iso-8859-1] Ramesh Krishnamurthy wrote:

            > dear all,
            > i have developed a logistic regression model to
            > predict the spatial distribution of three Himalayan
            > pheasants (that i have studied) viz. western tragopan,
            > himalayan monal and koklass. i now want to improve the
            > model by including the effect of spatial
            > autocorrelation found in the predicted probability. i
            > am trying calculate the autocovariate based on the
            > method suggested by Augustine et.al. published in
            > J.Applied Ecology. i am not clear about how does
            > iteration help in calculating the autocovariate and
            > how to decide on the optimum iteration required for
            > the data set. i would greatly appreciate if any one on
            > the list would educate me or suggest me the study
            > material on the subject.
            >
            > regards
            >
            > ramesh
            >
            >
            > =====
            >
            >
            > ____________________________________________________________
            > Do You Yahoo!?
            > For regular News updates go to http://in.news.yahoo.com
            >
            > --
            > * To post a message to the list, send it to ai-geostats@...
            > * As a general service to the users, please remember to post a summary of any useful responses to your questions.
            > * To unsubscribe, send an email to majordomo@... with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list
            > * Support to the list is provided at http://www.ai-geostats.org
            >

            CH3
            |
            N Nicholas Lewin-Koh
            / \ Dept of Statistics
            N----C C==O Program in Ecology and Evolutionary Biology
            || || | Iowa State University
            || || | Ames, IA 50011
            CH C N--CH3 http://www.public.iastate.edu/~nlewin
            \ / \ / nlewin@...
            N C
            | || Currently
            CH3 O Graphics Lab
            School of Computing
            National University of Singapore
            The Real Part of Coffee kohnicho@...


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