[R-sig-Geo] spatial correlation structure in lme

[Edzer Pebesma]

It would have helped us when you would have provided an example that was
reproducible for readers of this list.

I tried some things out, along that way, but didn't manage. Maybe you
could try the mixed-models list:

https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models

If you find out how these things work, feedback to this list would be
appreciated.

On 06/16/2012 04:52 AM, wudadan wrote:
> Dear R users,
> 
> I need some help in understanding the spatial correlation structure. Is
> there a document or paper that explains how to use spatial correlation
> structure such as "corExp"?
> 
> Here is the problem I run into. With the spatial correlation structure:
> 
>  "correlation = corExp(c(10,0.8),form = ~ north + east)"
> 
>  I tried to define the range and nugget as 10 miles and 0.8, respectively.

the help pages here suggest you'd have to add nugget=TRUE to the corExp
arguments.

> However, I got the error message "Error in initialize.corSpatial....Initial
> value for corSpatial parameters of wrong dimension". Can anyone tell me what
> this means?
> 
> I then tried the script:
> 
> "correlation = corExp(10,form = ~ north + east)"
> 
> It worked. However, it seems the range "10" was not used because after I
> changed it to "3", I got exactly the same estimation results. I'm wondering
> what the right way to do this.
> 
> Any advice is appreciated!
> 
> Best
> Gary
> 
> 
>  
> 
> 
>  
> 
> --
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de