Thanks for your reply,
?summary produce a multiple r2.
My dataset il similar to this one:
> a b c
> 1 -1.4805676 0.9729927 x
> 2 1.5771695 0.2172974 x
> 3 -0.9567445 0.5205087 x
> 4 -0.9200052 0.8279428 z
> 5 -1.9976421 0.9641110 z
> 6 -0.2722960 0.6318801 y
So, I would like to know the r2 for a~b for every factors levels.
Off course I can made the regression separately for every factors, but my
dataset have 68 factors...
----------
Francesco Nutini
PhD student
CNR-IREA (Institute for Electromagnetic Sensing of the Environment)
Milano, Italy
> From: rb...@atsu.edu
> To: nutini.france...@gmail.com; r-help@r-project.org
> Subject: Re: [R] [r] regression coefficient for different factors
> Date: Fri, 20 May 2011 08:07:59 -0500
>
> ?summary
>
> produces r^2 in 2nd to last line, as in,
> > set.seed(12); a=rnorm(100); b = runif(100); c = factor(rep(c('No',
> > 'Yes'),50)); df = data.frame(a,b,c)
> > head(df)
> a b c
> 1 -1.4805676 0.9729927 No
> 2 1.5771695 0.2172974 Yes
> 3 -0.9567445 0.5205087 No
> 4 -0.9200052 0.8279428 Yes
> 5 -1.9976421 0.9641110 No
> 6 -0.2722960 0.6318801 Yes
> > mod = lm(a ~ b*c)
> > summary(mod)
>
> Call:
> lm(formula = a ~ b * c)
>
> Residuals:
> Min 1Q Median 3Q Max
> -1.8196 -0.4754 -0.0246 0.5585 2.0941
>
> Coefficients:
> Estimate Std. Error t value Pr(>|t|)
> (Intercept) 0.2293 0.2314 0.991 0.324
> b -0.4226 0.3885 -1.088 0.280
> cYes 0.1578 0.3202 0.493 0.623
> b:cYes -0.5878 0.5621 -1.046 0.298
>
> Residual standard error: 0.8455 on 96 degrees of freedom
> Multiple R-squared: 0.07385, Adjusted R-squared: 0.04491
> F-statistic: 2.552 on 3 and 96 DF, p-value: 0.0601
>
> ------------------------------------------
> Robert W. Baer, Ph.D.
> Professor of Physiology
> Kirksville College of Osteopathic Medicine
> A. T. Still University of Health Sciences
> 800 W. Jefferson St.
> Kirksville, MO 63501
> 660-626-2322
> FAX 660-626-2965
>
>
> --------------------------------------------------
> From: "Francesco Nutini" <nutini.france...@gmail.com>
> Sent: Friday, May 20, 2011 4:17 AM
> To: "[R] help" <r-help@r-project.org>
> Subject: [R] [r] regression coefficient for different factors
>
> >
> > Dear R-helpers,
> >
> > In my dataset I have two continuous variable (A and B) and one factor.
> > I'm investigating the regression between the two variables usign the
> > command
> > lm(A ~ B, ...)
> > but now I want to know the regression coefficient (r2) of A vs. B for
> > every factors.
> > I know that I can obtain this information with excel, but the factor have
> > 68 levels...maybe [r] have a useful command.
> >
> > Thanks,
> >
> > Francesco Nutini
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@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.
> >
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