[R] Multivariate regression
Andris Jankevics
andza at osi.lv
Mon Oct 30 10:01:16 CET 2006
Also you can take a look on Partial Least Squares (PLS) regression.
http://www.statsoft.com/textbook/stpls.html
R-package: http://mevik.net/work/software/pls.html
Andris Jankevics
On Sestdiena, 28. Oktobris 2006 06:04, Ritwik Sinha wrote:
> You can use gee (
> http://finzi.psych.upenn.edu/R/library/geepack/html/00Index.html) or maybe
> the function gls in nlme.
>
> Ritwik.
>
> On 10/27/06, Ravi Varadhan <rvaradhan at jhmi.edu> wrote:
> > Hi,
> >
> >
> >
> > Suppose I have a multivariate response Y (n x k) obtained at a set of
> > predictors X (n x p). I would like to perform a linear regression taking
> > into consideration the covariance structure of Y within each unit - this
> > would be represented by a specified matrix V (k x k), assumed to be the
> > same
> > across units. How do I use "lm" to do this?
> >
> >
> >
> > One approach that I was thinking of is as follows:
> >
> >
> >
> > Flatten Y to a vector, say, Yvec (n*k x 1). Create Xvec (n*k, p*k) such
> > that it is made up of block matrices Bij (k x k), where Bij is a diagonal
> > matrix with X_ij as the diagonal (i = 1,.n, and j = 1,.,p). Now I can
> > use "lm" in a univariate mode to regress Yvec against Xvec, with
> > covariance matrix Vvec (n*k x n*k). Vvec is a block-diagonal matrix with
> > blocks of V along the diagonal. This seems like a valid approach, but I
> > still don't know how to specify the covariance structure to do weighted
> > least squares.
> >
> >
> >
> > Any help is appreciated.
> >
> >
> >
> > Best,
> >
> > Ravi.
> >
> >
> >
> >
> > -------------------------------------------------------------------------
> >--- -------
> >
> > Ravi Varadhan, Ph.D.
> >
> > Assistant Professor, The Center on Aging and Health
> >
> > Division of Geriatric Medicine and Gerontology
> >
> > Johns Hopkins University
> >
> > Ph: (410) 502-2619
> >
> > Fax: (410) 614-9625
> >
> > Email: rvaradhan at jhmi.edu
> >
> > Webpage:
> > http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html
> >
> >
> >
> >
> > -------------------------------------------------------------------------
> >--- --------
> >
> >
> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
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> > PLEASE do read the posting guide
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