
Hi you all,


 

I am studying the spatial overlap between two
species. I want to:

 

- Determine the spatial distribution of each of the
two species using a geostatistical approach by estimating the variogram and then apply the kriging and/or cokriging.



- Use the estimates predicted for each species to determine the ratio, to
evaluate de spatial distribution of the ratio estimates and then obtain the
overlap degree.



My questions are:



1 – What are the procedures that you recommend to test if the process is
stationary? I just assumed that the process is stationary?



2 - In my work there is clear east-west anisotropy. My questions regarding this
are:



i) Is there any test to evaluate its significance other than graphically? 

 

ii) Being a strong anisotropy it is more advisable to
study the spatial distribution, of the variable under study, in that direction?



3- Are there any cases where the Simple Kriging is more advisable than the
other forms of Kriging?



4- Besides Cross-validation residual and Cross validation z-scores, are there any test to evaluate the adequacy of different models? Is there any coefficient like AIC criterion to evaluate and choose the best-fitted model between several models or the decision is mainly done by graphical analysis? 





Thanks a lot for your help,

 

Best regards,Nuno Veiga

 

 









From:
Nuno Veiga [mailto:nmmv2002@hotmail.com] 

Sent: quarta-feira, 21 de Novembro
de 2012 9:35

To: Ivone Figueiredo

Cc: Teresa Moura

Subject: FW: Spatial Analysis
doubts



 



Bom dia,



 





O Pebesma respondeu-me isto, o que devo fazer? 





 





Devo só dizer que não gosto do senhor, pois não sabe
escrever o meu nome! 





 





키스 (Beijinhos em
coreano)





 



> Date: Tue, 20 Nov 2012 19:20:45 +0100

> From: edzer.pebesma@uni-muenster.de

> To: nmmv2002@hotmail.com

> Subject: Re: Spatial Analysis doubts

> 

> Dear Nunu, please post this message to r-sig-geo.

> 

> Wbr,

> 

> On 11/16/2012 11:51 AM, Nuno Veiga wrote:

> > 

> > Dear Edzer Pebesma

> > 

> > 

> > 

> > I am now working

> > on spatial data for a paper that I need to have ready by the end of

> > December. 

> > 

> > The main

> > objective is to estimate the overlap between two species. One is the
target of

> > the fishery, and the other one is caught as by-catch. 

> > 

> > 

> > The procedure

> > that I am intending to follow is the one described in "Applied
Spatial

> > Data Analysis with R":

> > 

> > 1- Determine the

> > spatial distribution of each of the two species using a
geostatistical approach

> > by estimating the variogram and then apply the kriging and/or
cokriging.

> > 

> > 2- Using the estimates predicted for each species to

> > determine the ratio, to evaluate de spatial distribution of the ratio

> > estimates and then obtain the overlap degree.

> > 

> > 

> > For doing

> > this I faced some problems that I will be very grateful if you help
me. The

> > problems/doubts are:

> > 

> > 1 – What

> > are the procedures that you recommend to test if the process is
stationary? I

> > just assumed that the process is stationary?

> > 

> > 2 - In my

> > work there is clear east-west anisotropy. My questions regarding this
are:

> > 

> > i) 

> > Is there any test to evaluate its significance

> > other than graphically? ii) 

> > Being a strong anisotropy it is more advisable

> > to study the spatial distribution of the variable under study, in
that

> > direction?

> > 

> > 

> > 

> > 3- Can you please

> > give me more details on the decision tree that you presented at page
210? There are any cases where the

> > Simple Kriging is more advisable than the other forms of Kriging?

> > 

> > 4- Besides Cross-validation residual and Cross

> > validation z-scores, are there any test to evaluate the adequacy of
different

> > models? Is there any coefficient like AIC criterion to evaluate and
choose the

> > best-fitted model between several models or the decision is mainly
done by

> > graphical analysis? 

> > 

> > 

> > Thanks a

> > lot for your help,Best

> > regards,

> > 

> > Nuno

> > Veiga 

> > 

> 

> -- 

> 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@wwu.de

> 







 		 	   		   		 	   		  
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