[R] How to combine to PCAs

[Ravi Varadhan]

Let  V = (v11, v12, ..., v1n, v21, v22, ..., v2n) be the matrix of data with
2*n columns.  Now, you simply do PCA on this data matrix.  
See the following paper, which has a related example:

Gabriel, K. R. and Odoroff, C. L. (1990). Biplots in biomedical research.
Statistics in Medicine, 9, 469-485. 

Ravi. 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Stefan Koenig
Sent: Thursday, June 05, 2008 4:47 AM
To: r-help at r-project.org
Subject: [R] How to combine to PCAs

Dear all:

Subjects were measured two times (t1 and t2) on different variables (v1 ...
vn). 
Between t1 and t2 there was an experimental manipulation. I computed two
PCAs for time-points t1 and t2. 

Is it possible to combine both PCAs in order to get only one set of
eigenvectors? Due to the experimental manipulation measurement values on
time points t1 and t2 changed for each subject.

Many thanks
Stefan
--

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.