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Re: GEOSTATS: Arc-info,geostat help

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  • Chaosheng Zhang
    ... Hello, Mark McCullars I am very much interested in what you are doing, and I also have done some work on statistical and GIS applications in environmental
    Message 1 of 3 , May 2, 1997
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      >Hello to all-
      >
      >I am new to the list and this is my first post. I am currently working on
      >a masters thesis in Geology. I have mapped a mineralized shear zone and
      >collected over 400 soil samples, had them analyzed and have put these
      >values into an Arc-info format. I have received some technical assistance
      >in doing this, and the maps themselves are for the most part complete.
      >
      >I am now working with the data in order to 'statistically' evaluate the
      >strength of relationships among some trace elements (As, Au, Ba, Co, Cu,
      >Mo, Pb, Sb, and Zn). I am currently using SigmaStat 2.0 to calculate the
      >Pearson Product Moment Correlation Coefficents for the elements.
      >
      >My questions are:
      >
      >Will i be able to digitize my geologic map and perform statistical
      >analysis of the values within particular lithologies (in Arcinfo) ?
      >and How difficult will this be?
      >
      >Are there any graphical means to represent the correlation coefficients i
      >have calculated with Sigmastat?
      >
      >What other software packages can you suggest for analyzing such a
      >database?
      >
      >Much thanks in advance-
      >
      >Mark McCullars
      >Grad Student
      >Auburn University
      >mcculjm@...
      >

      Hello, Mark McCullars

      I am very much interested in what you are doing, and I also have done some
      work on statistical and GIS applications in environmental geochemistry
      (trace elements). The following are some tips for you, based on my own
      experiences.

      * Trace elements usually do not follow normal distribution. Before
      statistical analysis, you had better transform the datasets (to follow
      normality).

      * Outlying values do not belong to the population of your samples, therefore
      you should detect them, and treat them in some special way (delete or
      replace). Outlying samples should also be detected.

      * Geologial maps could be digitized, and then you can overlay your element
      contents with the maps. Therefore, you could explain some phenomena based
      on the spatial distribution maps. However, when you use geological maps,
      you should be careful that your samples may not always follow the geological
      feature (such as bedrock), because the geological maps are summarized (based
      on their scales).

      * You can also carry out some spatial analysis, such as geostatistics (study
      the variograms in detail), spatial autocorrelation and fractal, etc.

      * You should not expect too high on GIS, as it is only a tool for us.

      Cheers,

      Chaosheng Zhang

      Dr. Chaosheng Zhang
      Division of Geochemistry
      Geological Survey of Sweden, SGU
      P.O. Box 670
      S-751 28 Uppsalla
      SWEDEN
      Tel: +46 18 179290
      Fax: +46 18 179210
      E-mail: chaosheng.zhang@...

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    • Benjamin S. Warr
      How good is factorial kriging at image filtering ? Have the accuracy of predictions from image data analysed in this way been tested anywhere ? Ben Warr, Soil
      Message 2 of 3 , May 2, 1997
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        How good is factorial kriging at image filtering ? Have the accuracy of
        predictions from image data analysed in this way been tested anywhere ?

        Ben Warr, Soil Science, Reading University.




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