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[ai-geostats] sampling density / sampling interval

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  • Mahdi Osman
    Thanks a lot! My interest is to take econonomically feasible number of samples for further detalied examination of soil nitrogen gross- immobilisation,
    Message 1 of 1 , Jan 4, 2005
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      Thanks a lot!

      My interest is to take econonomically feasible number of samples for further
      detalied examination of soil nitrogen gross- immobilisation, mobilisation
      etc. based on my variogram results. I understand the larger the number of
      samples the better the results. But I would like to achieve optimum number
      of samples.

      My questions now are:

      Is it sufficient to look at the range? Do I have to consider the whole range
      of influence or how much of the range? Do I have to take into accout the
      nugget? Is it possible to say the size of nugget that acceptable in my type
      of work?

      Many thanks for your help and time.

      Regards

      Mahdi



      > Hello,
      >
      > Is your goal the mapping of nitrogen across your field or
      > only the estimate of the average value over that field.
      > The range of the semivariogram should provide an indication
      > of the average distance of autocorrelation that you could
      > use as spacing interval. Usually, the more samples, the better.
      > See how many you can afford and how many are necessary given
      > the range of autocorrelation. I guess the semivariogram has
      > been estimated from data previously collected on the same
      > field, so this information should also be accounted for,
      > assuming that it doesn't change too much over time.
      >
      > Hope it helps,
      >
      > Pierre Goovaerts
      >
      <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
      >
      > Dr. Pierre Goovaerts
      > President of PGeostat, LLC
      > Chief Scientist with Biomedware Inc.
      > 710 Ridgemont Lane
      > Ann Arbor, Michigan, 48103-1535, U.S.A.
      >
      > E-mail: goovaerts@...
      > Phone: (734) 668-9900
      > Fax: (734) 668-7788
      > http://home.comcast.net/~goovaerts/
      >
      >
      <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
      >
      > On Mon, 3 Jan 2005, Mahdi Osman wrote:
      >
      > > Dear, Prof Goovaerts,
      > >
      > >
      > >
      > > I am estimating nitrogen mineralisation rate on a 25 X 25 ha field. One
      > of
      > > my efforts is to find out optimum sampling density to examine nitrogen
      > > mineralisation in my plot. How can I exploit a semivariogram to answer
      > this
      > > question? Does anyone have suggestions and also some relevant
      > literature?
      > >
      > > Your publications have been very helpful to me to so far.
      > >
      > > Thanks for your help
      > > Mahdi
      > >
      > >
      > > -
      > >
      > > --
      > > -----------------------------------
      > > Mahdi Osman (PhD)
      > > E-mail: m_osm@...
      > > -----------------------------------
      > >
      > > +++ GMX - die erste Adresse für Mail, Message, More +++
      > > 1 GB Mailbox bereits in GMX FreeMail http://www.gmx.net/de/go/mail
      > >
      >

      --
      -----------------------------------
      Mahdi Osman (PhD)
      E-mail: m_osm@...
      -----------------------------------

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