[R] Need for advise for Correspondence Analysis

[Martin Henry H. Stevens]

You may want to look at the documentation for the vegan package.
Hank Stevens
On Jun 22, 2004, at 2:19 PM, christophe grova wrote:

>
> Dear R users,
>
> I m quite a novice in using R for factor analysis and I would need 
> some help to choose the right function.
> I have a contingency table and I would like to perform a  
> Correspondence analysis on this table, followed by a hirarchical 
> clustering of my variables projected in on the first principal 
> components.
>
> Here are my question :
>
> - what is the more appropriate function to do so ... I already tried 
> by using the function 'corresp' in the MASS package
> - it seems to work ... but how is it possible to get all the 
> information concerning the non-centered PCA used by corresp 
> (eigen-values, inertia, scree plot, square cos, ....)
>
> In a second step I would like to use hirarchical clustering from the 
> results of the correspondence analysis ...
>
> If "Table" is my contingency table (i.e., the number of individuals 
> seen in each case) ... I tried to implment it as follow (for the 2 
> first components for instance, but I would be interesting at looking 
> to the other components ...I did not manage to get the eigen values !) 
> :
>
> A <- corresp(Table, nf = 2)
> biplot(A)
> hc <- hclust(dist(A$cscore), "ward")
> plot(hc)
>
> Is that ok ??? ... here it is exemplae using Ward method for 
> clustering ...
> I would also be interested in using method of mutual neighbors  to 
> identify the clusters ... is it possible using hclust ?
>
> Any help would be really appreciated,
>
> Best regards ...
>
> Christophe
>
> ***************************
> Christophe Grova, PhD
> PostDoc - EEG department
> Montreal Neurological Institute, McGill University
> 3801 University Street, Montreal, Quebec, Canada, H3A 2B4
> email : christophe.grova at mail.mcgill.ca
> tel : (514) 398 2184
> fax : (514) 398 8106
> web: http://idm.univ-rennes1.fr/users/grova
> ***************************
>
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>
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Dr. Martin Henry H. Stevens, Assistant Professor
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