g.setproj, r.proj, rant about s.surf.**

[Brad Robbins (BIO)]

Nearest neighbor analysis as first introduced by Hopkins and Skellman
(1954) is a technique devised to study spacing of plant individuals (i.e.
the pattern of points in a plane; see Pielou 1969).  A major assumption of
this technique is that each individual can be represented by a point in
space surrounded by some circle of radius r, which implies geometric
regularity.  For some individuals this technique seems to work fine 
although Simberloff (1978) pointed out that nearest neighbor techniques
tend to overestimate the degree of spatial regularity in ant-lion
populations.  Because patches of interest are more typically 
convoluted in nature, difficulties arise when trying to apply nearest 
neighbor analysis.  For example, if we are interested in the spatial 
pattern of some resource A we might ask how patches of A are distributed 
across a landscape.  If A is found in regularly shaped patches then 
nearest neighbor analysis might prove appropriate.  However, if A is 
distributed in highly convoluted patches or in linear patches we face an 
inherent problem of where to place our point of measure.  Do we 
arbitraily select some point in the patch or try to determine the 
geometric center?  If the point of measure is arbitrary then I can 
imagine 2 patches, one on either side of a third with equivalent nearest 
neighbor values but which in reality are very different from one another.
             

    

Brad Robbins						Dept. of Biology
brobbins at chuma.cas.usf.edu				Univ. of South Florida


On 30 Aug 1994, Timothy Keitt wrote:

> 
> >
> >Have you given any thought to how you might deal with the inherent 
> >problems of nearest neighbor techniques when dealing with non-point data?
> >
> 
> No.  Could you elaborate?
> 
> T.
> 
> 
> 
>