[R-sig-eco] Do we have to cut a dendrogramm at a specific level or not

[Jens Oldeland]

Dear Group,

I am currently preparing a lecture on 'Cluster Analysis' and I found two 
very different ways to interpret a dendrogram. The first option is to 
'cut' a dendrogram at a specific height, like it is possible with the 
cluster package.

The second option identifies the 'optimal clusters' at different 
heights, for example see McCune etal. 2002 Analysis of Ecological 
Communities Figure 11.3.

Now these are two very different ways of interpreting and I am wondering 
which one is 'allowed' or perhaps the more practical way? Is it possible 
to combine both? I.e. first search for the optimal cut level and then 
adjust each clustering height by aggregation at heigher levels?

Regards,

Jens