[R] How to combine to PCAs
mark_difford at yahoo.co.uk
Thu Jun 5 13:45:16 CEST 2008
>> Is it possible to combine both PCAs in order to get only one set of
Yes there is: statis() in the ade4 package is probably what you want. In
short, it does a k-table analysis that will give you a common
ordination/position. It also shows how each time-set deviates from that
common position. RV-coeff. showing how well the two tables match each other
&c. Excellent graphical summaries...
The method is quite complex, but if you read French then there is some very
good documentation on their site:
Here you will also find a couple of papers (in English) on the method.
There's also a list. Stephane (Dray) replies to many of the questions and
writes and speaks English well.
Stefan Koenig wrote:
> 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
> R-help at r-project.org mailing list
> PLEASE do read the posting guide
> and provide commented, minimal, self-contained, reproducible code.
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