[R] non-linear trends in kriging model

[David Pleydell]

Thanks Paulo

Option 1 seems to work nicely, but I'm not sure how to specify the 
likelihood function so that I can calculate AIC for comparison with models 
fitted with likfit?

David

At 12:24 01/10/2003 +0200, you wrote:
>David
>
>Indeed, the trend term in geoR must be a linear one.
>You can:
>1) fit you model by alternating between using nls() and passing the
>residuals to the functions in geoR
>or
>2) try trying to fit using the functions in the nlme() package
>
>Regards
>P.J.
>
>On Tue, 30 Sep 2003, David Pleydell wrote:
>
> > Hi
> > I am struggling to fit a non-linear trend using the
> > likfit function in geoR.
> >
> > Specifically I want a sigmoidal function, something
> > like SSfpl in the nls package to fit the trend.  But
> > it seems trend.spatial in geoR only works with lm or
> > glm type models.
> >
> > Any ideas how I can specify the model to calculate the
> > kriging parameters using REML, including the
> > parameters of a sigmoidal trend function (such as
> > SSfpl)?
> >
> > Thanks
> > David
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> >
> >
>
>Paulo Justiniano Ribeiro Jr
>Departamento de Estatística
>Universidade Federal do Paraná
>Caixa Postal 19.081
>CEP 81.531-990
>Curitiba, PR  -  Brasil
>Tel: (+55) 41 361 3471
>Fax: (+55) 41 361 3141
>e-mail: pj at est.ufpr.br
>http://www.est.ufpr.br/~paulojus

************************************************
David Pleydell
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Telford Institute of Environmental Systems
School of Environment and Life Sciences
University of Salford
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phone: +44 161 2952094
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