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Re: Fw: AI-GEOSTATS: Small data set

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  • José Quintín Cuador Gil
    Dear Isobel, I have received your analysis. I going to reproduce this analysis in details as you suggest me. Thank you very much for your kindness Best regards
    Message 1 of 1 , Apr 7 11:33 PM
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      Dear Isobel,
      I have received your analysis. I going to reproduce this analysis in details
      as you suggest me.
      Thank you very much for your kindness

      Best regards
      José

      ----- Original Message -----
      From: "Isobel Clark" <drisobelclark@...>
      To: "Jos?_Quint?n_Cuador_Gil" <cuador@...>
      Sent: Sunday, April 11, 2004 12:36 PM
      Subject: Re: Fw: AI-GEOSTATS: Small data set


      José

      I have had a quick look at your data. You have
      sufficient data for a geostatistical analysis, but you
      have two problems which show up in these data files:

      Data1: this large scale data file shows a very strong
      trend accounting for around 99% of the variation
      between the values. Your values are high in the
      northwest and drop off consistently to the southeast.
      Once the trend is removed, you have a slightly erratic
      semi-variogram which can be modelled with a spherical
      model, range of influence 3,000 (metres?). Sampling
      should be at least 2,000 (metres?) coverage to get any
      reliable mapping. Universal kriging is needed to
      account for the trend. I used a search radius of
      10,000 for UK because of needing to estimate the trend
      component.

      Data2: this (geostatistical?) cross of values located
      in the far south-east of your study area shows very
      strange behaviour in several respects:

      (a) the values seem to be clustered into three
      groups, 4 samples around 71, 2 samples around
      74 and a cohesive group in the 72.2-73 range.


      (b) the general trend of data set 1 and the
      values of the local samples in data set 1
      are almost exactly 12 (units?) below the
      average of the samples in data set 2.

      In short, I like your Data1 samples but am very
      worried about your Data2 samples in the same context.

      I have attached a pdf file with some screen dumps of
      part of my analyses. I also attach a copy of your data
      which can be used with our demo software.

      Download from http://geoecosse.bizland.com/softwares

      You can reproduce most of what I have done this way. I
      have combined the files with the samples identified by
      'zone code' -- 1 for Data1, 2 for Data2.

      Isobel




      III Simposio Internacional sobre Manejo Sostenible de Recursos Forestales,
      Universidad de Pinar del Rio, Cuba 21-23 Abril del 2004.
      Telef:(53)(82)779363, Fax:(53)(82)779353 email:fhernandez@...


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