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kriging

4 messages · Paulo Justiniano Ribeiro Jr, Dave Depew, Tomislav Hengl

Original
Dave Depew
# 
Hi all,
I have a data set that I would like to krige to interpolate between 
transects. There is a non-linear trend between two of the variables...my 
impression from reading the gstat help file is that there must be a 
linear relationship between the data to use universal kriging?
Second, would a method of non-linear regression followed by modelling of 
the residuals with a semivariogram be an appropriate solution?

Thanks,

Dave
Paulo Justiniano Ribeiro Jr
# 
Dave,

what is necessary for UK is a relation expressed by a linear model, not
necessaraly a linear relation between the variables.
e.g. you could have a second degree polinomial and still work within the
scope of universal kriging.
On Mon, 16 Jun 2008, Dave Depew wrote:

            

      
      
      
    

        

      
      
    

        
Paulo Justiniano Ribeiro Jr
LEG (Laboratorio de Estatistica e Geoinformacao)
Universidade Federal do Parana
Caixa Postal 19.081
CEP 81.531-990
Curitiba, PR  -  Brasil
Tel: (+55) 41 3361 3573
Fax: (+55) 41 3361 3141
e-mail: paulojus AT  ufpr  br
http://www.leg.ufpr.br/~paulojus

  
  


  


      

    

    

      
      

        


  

        

      Dave Depew
    

    

      
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Ok,
What about higher order polynomials? I have fitted one using a gam to 
the data which which helps to normalize the residuals, and reduce the 
variance of the residuals.
Is it simply a matter of plugging in the function into the gstat command 
line? Or is it simpler to krig the residuals and then add the trend back 
to the interpolated residual grid?

        
Paulo Justiniano Ribeiro Jr wrote: