[R] princomp - varimax - factanal

[William Revelle]

At 3:00 PM +0100 1/30/09, Alberto Maceda Veiga wrote:
>Hi!
>
>I am trying to analyse with R a database that I have previously analysed
>with SPSS.
>
>Steps with SPSS:
>
>Factorial analysis
>  Extraction options : I select = Principal component analysis
>  Rotation: varimax

Unfortunately, SPSS labels principal components as a factor model. 
It is not.   So, extracting the first n factors by using factanal 
will give you a very different solution than the first n principal 
components.


>
>Steps with R:
>
>I have tried it with varimax function with factanal or with princomp...and
>the results are different of what I have with SPSS. I think that varimax
>function is incorporated in factanal function.
>
>
>Does anybody know which are the instructions into R to do exactly the same
>of what I have done with SPSS???

To duplicate the SPSS analysis try using the psych package.

The principal function in the psych package will extract the first n 
components (defaults to 1) and then by default rotate using varimax.

library(psych)
pc <- principal(my.data,n)  #where n is the number components you 
want to extract

Let me know if this matches the SPSS output.

Bill






>
>
>
>Thank you very much!
>
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>
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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/
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