weird results w/ prcomp-princomp
On Fri, 2005-04-08 at 11:12 +0200, Alessandro Bigi wrote:
I am doing a Principal Component Analaysis (PCA) on a 44x19 matrix. with
> princomp(x,cor=TRUE,scores=TRUE)
and
> prcomp(x,scale=TRUE,center=TRUE)
The resulted eigenv. and rotated matrix are the same (as expected), however the sum of eigenvalues is lower than 19 (number of variables).
What about the sum of squared sdev? (Hint, the "prcomp" help page says that the returned sdev are the square root of the eigenvalues. While "princomp" help does not say this explicitly, it says that "sdev" are standard deviations). cheers, jari oksanen
Jari Oksanen -- Dept Biology, Univ Oulu, 90014 Oulu, Finland Ph. +358 8 5531526, cell +358 40 5136529, fax +358 8 5531061 email jari.oksanen at oulu.fi, homepage http://cc.oulu.fi/~jarioksa/