[R-sig-Geo] Comparing spatial point patterns - Syrjala test

[Barry Rowlingson]

jiho wrote:

> Thank you very much for this reference. However the problem it is  
> dealing with is not really similar to the one I target. In this paper  
> the authors assess the differences in positions of neurones in a 2D  
> plane between three groups of patients, with replicates in each group.  
> So the data of interest are the coordinates.
> In my case, the positions of sampling stations are fixed (and on a  
> grid if that helps [1]) and I want to assess the differences in  
> abundances of two groups at these positions. So the data of interest  
> are the abundances (normalized to remove the effect of total  
> population sizes), and more specifically, the way the abundances are  
> distributed on these points. Maybe the subject of this email is not  
> correctly stated then. I am not a native english speaker and when it  
> comes to technical terms, it is even worse.
> 

  "Spatial Point Pattern Analysis" only refers to cases where the 
locations of the points are 'interesting', which usually means they are 
generated by a stochastic process - like tree locations in a natural 
forest rather than rows of trees in a plantation.

  Analysis of data that comes from spatial locations that are 
'uninteresting' are another branch of statistics altogether. It will 
probably end up being generalised linear modelling with 
spatially-correlated errors, and how you deal with the correlations is 
the interesting part.

  See if you can write down a model for your data and include a 
smoothly-varying spatial error term.... Then maybe we can find some R 
code to solve it. I don't think we'll find it in Spatstat, which I think 
is still exclusively spatial point pattern analysis. Have a look at 
geoRglm maybe...

Barry