[R] princomp

Peter Ho peter at esb.ucp.pt
Thu Sep 9 12:55:24 CEST 1999


In using the princomp function for Principle components analysis does setting

1) cor=TRUE result in princomp using a correlation matrix as in princomp(crimes,
cor = TRUE) and

2)cor=FALSE, a covariance matrix as in princomp(scale(crimes, scale = TRUE, center
= TRUE), cor = FALSE)

The help file explains the difference in scaling, but it is unclear to me if
automatic scaling (cor=TRUE) gives standardisation of data like in the case when

Rusults using both methods are quite similar though.
Can anyone explain the difference.



Peter Ho
Escola Superior de Biotecnologia
Universidade Católica Portuguesa
Rua Dr. António Bernardino de Almeida
4200 Porto
Tel: ++351-2-5580043

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