[R] multiple autocorrelation coefficients in spdep?

From: Ignacio Colonna <iacolonn_at_uiuc.edu>
Date: Mon 25 Apr 2005 - 21:36:51 EST


Hello,

            Has anyone modified the errorsarlm in the R package spdep to allow for more than a single spatial autocorrelation coefficient (i.e. 'lambda')?

            Or, if not, any initial suggestions on how to make that modification? I have looked at the source code for the function and realize that any attempt to do it on my own would require much dedication, so would like to check whether someone has done it already. My R programming skills are very elementary.  

Specifically I would need to specify 2 different lambdas in a dataset, one for each group. I am performing a regression of grain yield against a number of soil variables, for 2 different years, where the regression includes terms for year*soil variables interaction. The spatial structure of the error is clearly different between these years, and I would thus like to fit different lambdas to them, if possible. Of course one option is to just run 2 separate regressions, but if the possibility of fitting more than 1 lambda does not seem too remote, I think fitting a single model offers some advantages.  

Thanks in advance,  

Ignacio  

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