Loading ...
Sorry, an error occurred while loading the content.

GEOSTATS: Tom Mueller's comments

Expand Messages
  • Donald Myers
    I think that you could identify the problem a bit more explicitly. The difference between the different choices of the parameters in the exponential and
    Message 1 of 1 , Aug 27, 1998
    • 0 Attachment
      I think that you could identify the problem a bit more explicitly. The
      difference between the different choices of the parameters in the
      exponential and gaussian variogram models is the difference between a
      parameter and an "effective range". This distinction has long been known in
      the geostatistical literature, the problem arises because neither the
      exponential nor the gaussian has a true range, i.e., a distance at which
      the variogram is constant (as occurs with a spherical model). Instead the
      "effective range" is the distance at which the value of the variogram is
      95% of the sill.

      It is likely that the reason that Surfer and SAS do not recognize this
      distinction is that neither is really a geostatistical package, early
      versions of Surfer did not allow the user to specify a variogram model for
      kriging and a linear model was assumed. In the case of a linear model, the
      slope does not affect the kriging weights (it does affect the kriging
      variances). It is likely that the programmers were not really familiar with
      geostatistics and the geostatistical literature.

      It is nice to see other software packages incorporate geostatistical tools
      but sometimes the implementations leave a lot to be desired.

      DEMyers
      Department of Mathematics
      University of Arizona
      Tucson, AZ 85721
      htttp://www.u.arizona.edu/~donaldm


      --
      *To post a message to the list, send it to ai-geostats@....
      *As a general service to list users, please remember to post a summary
      of any useful responses to your questions.
      *To unsubscribe, send email to majordomo@... with no subject and
      "unsubscribe ai-geostats" in the message body.
      DO NOT SEND Subscribe/Unsubscribe requests to the list!
    Your message has been successfully submitted and would be delivered to recipients shortly.