From: Pedram Rowhani <rowhani_at_geog.ucl.ac.be>

Date: Mon 02 Apr 2007 - 15:05:32 GMT

http://www.geo.ucl.ac.be/Recherche/Teledetection/index.html

R-help@stat.math.ethz.ch 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. Received on Tue Apr 03 01:13:37 2007

Date: Mon 02 Apr 2007 - 15:05:32 GMT

Dear John and Michael,

sorry for the poor explanation of my question.

What I am looking for is the partial R-squares, to estimate the
proportion of unexplained variation of y that becomes explained with
the addition of variable x

cr.plots does give me the plots but I am looking for a way to get the
actual partial R squares, which would correspond to the R squares of
those plots

I hope that things are a bit more clear now

I guess I can calculate the SSE's and SSR's of the different models myself and then use the formula for partial R square but things would be just simpler if there was already a function implemented in R

Thanks again

Pedram

At 16:20 02/04/2007, John Fox wrote:

>Dear Michael and Pedram,

*>
**>I'm afraid that Pedram's question is unclear, since the subject line refers
**>to "partial R" (which might have been intended as "partial r," or "partial
**>correlation"), while the message itself refers to "partial regression
**>coefficients."
**>
**>The latter are simply the coefficients returned by lm(); there is a
**>partial.cor() function in the Rcmdr package that computes partial
**>correlations. It's so simple, that I'll just reproduce it here:
**>
**>partial.cor <-
**>function (X, ...)
**>{
**> R <- cor(X, ...)
**> RI <- solve(R)
**> D <- 1/sqrt(diag(RI))
**> R <- -RI * (D %o% D)
**> diag(R) <- 0
**> rownames(R) <- colnames(R) <- colnames(X)
**> R
**>}
**>
**>cr.plots() in the car package produces partial-residual plots
**>("component+residual plots") but returns neither partial correlations nor
**>partial-regression coefficients.
**>
**>Regards,
**> John
**>
**>--------------------------------
**>John Fox
**>Department of Sociology
**>McMaster University
**>Hamilton, Ontario
**>Canada L8S 4M4
**>905-525-9140x23604
**>http://socserv.mcmaster.ca/jfox
**>--------------------------------
**>
**> > -----Original Message-----
**> > From: r-help-bounces@stat.math.ethz.ch
**> > [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Michael Kubovy
**> > Sent: Monday, April 02, 2007 9:16 AM
**> > To: Pedram Rowhani
**> > Cc: r-help@stat.math.ethz.ch
**> > Subject: Re: [R] partial R
**> >
**> >
**> > On Apr 2, 2007, at 5:49 AM, Pedram Rowhani wrote:
**> >
**> > > i am wondering if there is a command in R that will give me the
**> > > partial regression coefficients
**> >
**> > To answer your question, you could have started with
**> > RSiteSearch('partial regression')
**> >
**> > It's then likely that you would figured out that one way to proceed is
**> > install.packages('car')
**> > ?cr.plots
**> >
**> > (You may have to restart R to get the help on a newly-installed
**> > package.)
**> > _____________________________
**> > Professor Michael Kubovy
**> > University of Virginia
**> > Department of Psychology
**> > USPS: P.O.Box 400400 Charlottesville, VA 22904-4400
**> > Parcels: Room 102 Gilmer Hall
**> > McCormick Road Charlottesville, VA 22903
**> > Office: B011 +1-434-982-4729
**> > Lab: B019 +1-434-982-4751
**> > Fax: +1-434-982-4766
**> > WWW: http://www.people.virginia.edu/~mk9y/
**> >
**> > ______________________________________________
**> > R-help@stat.math.ethz.ch 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.
**> >
*

Pedram Rowhani Ardekani

University of Louvain

Department of geography

Place Louis Pasteur, 3

1348 Louvain-la-Neuve (Belgium)

tel (+32) 010/47.28.70 fax (+32) 010/47.28.77 e-mail rowhani@geog.ucl.ac.be

http://www.geo.ucl.ac.be/Recherche/Teledetection/index.html

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