[R] R vs SPSS output for princomp

[Prof Brian Ripley]

On Tue, 6 May 2003, James Howison wrote:

> I guess I'm expecting an interface for PCA not too dissimilar to that 
> of factanal (as it is in other statistical packages).  Perhaps there 
> are sounds statisical reasons for not wanting to hide this step from 
> the user but perhaps it is interesting to you to know people's 
> expectations when using the princomp function.

Well, many other packages confuse (hopelessly) PCA and factor analysis,
including SPSS.  They are separate statistical methods with very different
purposes, that for factanal being quite rarely appropriate.  R is not
written to reproduce the mistakes of other packages, but to implement
sound statistical practice.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595