R help - Dec 2006 - FW: test of spatial dependence?? - ask a geographer (was ask an ecologist)?

No, you do not necessarily need the XY coordinates. You can also use polygon
(field, in your case) adjacency information. See Rogerson, Peter A. 2001.
_Statistical methods for geography_. Thousand Oaks: Sage.

You might also look at GeoDA, a free and soon-to-be open source spatial
analysis package. For your application, it might be easier to use than R. Go
to https://www.geoda.uiuc.edu/.

	Marshall Feldman
	Center for Urban Studies and Research
	The University of Rhode Island

-----Original Message-----
From: Milton Cezar Ribeiro [mailto:milton_ruser at yahoo.com.br] 
Sent: Wednesday, December 06, 2006 8:26 AM
To: David Farrar; Xu Yuan; r-help at stat.math.ethz.ch
Subject: Re: [R] test of spatial dependence?? - ask an ecologist?

I never used it, but I beleave that it is a job for "mantel.rtest()"
available on "ade4" package.
   
  In fact Farrar are right, you will neet the XY coordinates. Give a look at
"Legendre & Legendre" text book.
   
  HTH,
   
  Miltinho
  Brazil

David Farrar <dfarrar at newrvana.com> escreveu:
  

In addition to the 25 numbers, I assume you have coordinates of each field.
Otherwise, I don't understand what you are trying to do. I think ecologists
like to use a test due to Mantel in this situation. 

The prefix "auto" means "self," of course, the idea being
that measurements
of the same variable under different conditions are correlated. I guess this
would be a case of "autodependence." For correlation versus
dependence,
check your intro stats book. 

de nada, 
X'X 

Farrar 


Xu Yuan wrote:
hello R-friends,

I am a R beginner and try to ask a basic question:

How to test the spatial dependence of a column of data? for example, I have
25 agricultural fields, and I measure the average slope (%) or pH for each
field. All I have is 25 numbers.

PS, could someone confirm that "spatial dependence" is equivalent to
"spatial correlation" or "spatial autocorrelation" or not.

Thank you very much.
XY

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Dr. Marshall Feldman, PhD
Director of Research and Academic Affairs
Center for Urban Studies and Research 
The University of Rhode Island
email: marsh @ uri.edu (remove spaces) 
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