[R-sig-ME] spatial correlation structure for GLS (nlme)

[Ing. Agr. Agustín Alesso]

Hello,

I need some advice to include a spatial correlation structure to an
ANOVA one-way GLS model. 

First, I fit a simple model asuming uncorrelated errors and plotted the
residuals variogram which showed the spatial autocorrelation. Then, with
gstat package, I fit some models to guess initial values for corSpatial.
The best model fitted has a nugget efect with to spherical structures (2
ranges).
Before adding more complexity to the model, I tried to fit few models
with basic predefined corStructures and then looking at their
residuals variograms. Although including correlation results in smaller
AICs, the variograms still showing strong spatial correlation of
residuals.  

Is there a way to bluid a spatial correlation structure including two
ranges?

Thanks in advance,



-- 
Ing. Agr. Agustín Alesso
Dpto. Ciencias del Ambiente
Fac. Cs. Agrarias - UNL
Kreder 2805 - S3080HOF - Esperanza
Tel: 03496-428575 int 337/256