[R-sig-Geo] Duttileul's method

[Roger Bivand]

On Wed, 4 Apr 2007, W. Daniel Kissling wrote:

> Hi all,
> 
> I am currently looking for a possibility to calculate the geographically
> effective degrees of freedom of a (non-spatial ordinary least squares)
> regression model in the presence of spatial autocorrelation within a
> gridded dataset. My regression model has spatial autocorrelation in the
> residuals (indicated by Moran's I values) but I do not want to use a
> spatial model (e.g. errorsarlm in package spdep). Instead, I would like
> to calculate the significance tests of my (non-spatial) regression model
> using the reduced degrees of freedom. I know that there is the
> Duttileul's method (Duttileul 1993) in other software packages which
> does exactly this. Is there anything comparable in R? Is there a
> function in the spdep (or any other) package which allows this to be
> computed?

There is no implementation of degrees of freedom adjustment in contributed 
packages that I am aware of, and RSiteSearch() also gives no hits, so this 
seems to be correct. Essentially, to adjust the df you may need to fit the 
spatial model anyway, to get an estimate of the loss of df caused by 
autocorrelation. There is also a recent paper by Griffith in AAAG, 
December 2005, pp. 740-760.

Roger

> 
> I am very happy to get feedback.
> 
> Best regards
> Daniel
> 
> --------------------------------------------------------------------
> W. Daniel Kissling
> Community & Macroecology Group
> Institut für Zoologie, Abteilung Ökologie
> Johannes Gutenberg-Universität Mainz
> D-55099 Mainz, Germany
> 
> Tel. +49 (0)6131 3925200  
> Fax +49 (0)6131 3923731 
> E-mail: kissling at uni-mainz.de
> 
> Personal: http://www.danielkissling.de/
> Research Group: http://www.oekologie.biologie.uni-mainz.de/commecol/main.html
> Virtual Institute Macroecology: http://www.ufz.de/index.php?en=6302
> Centre of Macroecology: http://www.macroecology.ku.dk/
> 
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no