[R] NMDS and varimax rotation

[William Revelle]

At 9:54 PM +0200 9/9/08, Bernd Panassiti wrote:
>hello,
>
>subsequently to a NMDS analysis (performed with metaMDS or isoMDS) is
>it possible to
>rotate the axis through a varimax-rotation?
>
>Thanks in advance.
>
>Bernd Panassiti


Bernd,


Yes.  The output of isoMDS is an object with points and stress.

consider the following example:

  test.data <- Harman74.cor$cov      #twenty four mental measurements
  harm.dist <- sqrt(2*(1- test.data) )  #convert correlations to distances
harm.iso <- isoMDS(harm.dist,k=2)  # find the multidimensional solution
harm.varimax <- varimax(harm.iso$points) #rotate with varimax
op <- par(mfrow=c(1,2))
plot(harm.iso$points, main="unrotated")
plot(harm.varimax$loadings,main="rotated")

Bill



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-- 
William Revelle		http://personality-project.org/revelle.html
Professor			http://personality-project.org/personality.html
Department of Psychology             http://www.wcas.northwestern.edu/psych/
Northwestern University	http://www.northwestern.edu/
Use R for psychology                       http://personality-project.org/r