Hi,


I'm not really a specialist of spatial models but I'll try to answer your
question as I can..

You could test for global spatial autocorrelation using Moran's I with spdep
Also, you could test for local autocorrelation using LISA, Local Moran's I,
and visualizing it with a moran scatterplot. You could plot LISA results so
as to see which plots seem influenced by neighbors, and which ones do not

Finally, you could integrate spatial relationships and possible
autocorrelation in your model using a SAR model: lag or error (or even
mixed, durbin model), it depends. spdep iplements Lagrange Multiplier tests
to choose which one would fit the best.

Let me advise you to read ASDAR book or the Anselin
document<http://docs.google.com/viewer?a=v&q=cache:N-oMX8J_Ax8J:geodacenter.asu.edu/system/files/rex1.pdf+luc+anselin+spatial+regression&hl=fr&gl=fr&pid=bl&srcid=ADGEESgnaCfu_2reqY-W7RN74hRHrk3rzih_6TQv9ZKgAarKpWIfadW5lZz1Lx1lO_MBMqbUZxsida7rBnbGxdyGI4u_uq7tcFn3tt6poNcLCKvZceeXFh_c4pwPRB1PUgQdpZIoI4HC&sig=AHIEtbTu45vUqPjzPyHfH2MK1N8yYZQcSw>,
a workbook on spatial regression. Also, yuri zhukov's harvard resource
http://www.people.fas.harvard.edu/~zhukov/spatial.html is also a very good
material.

You'll find all what you need in spdep!

I think that people knowing more the subject than me will also respond your
question, but I hope this helps.


Mathieu

2011/6/20 Tim Whitfeld <whitf015@umn.edu>

> I'm new to the list and am hoping for some assistance with analysis for a
> paper that investigates patterns of tree diversity in the tropics. For this
> project I surveyed all trees in a 19 quarter hectare plots in a tropical
> lowland rainforest. I'm interested in testing whether the observed
> correlation between patterns of diversity (measured by mean evolutionary
> distance between all trees in each plot) and total tree area (measured by
> total cross sectional area of tree trunks at 1.3 m above ground level, i.e.,
> the basal area) is confounded by plot location (measured by UTM
> coordinates). In other word, I want to test whether spatial auto correlation
> is driving the observed relationship. I have performed a partial Mantel test
> that indicates no spatial autocorrelation but I'd also like to test this
> with a more sophisticated approach using simultaneous autogressive models. I
> understand SAR models can be implemented in R using the spdep package. I
> have used R with other packages but am no expert. Does anyone have an
> example or a walk through of how to run the type of analysis I'm interested
> in and also how to interpret the results?
> With thanks, Tim
>
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