Francesco, do you just want a separate regression for each level of your factor c? You could write a loop - looping through levels of c:
for(i in levels(c)){ select your data here and write a regression formula } On Fri, May 20, 2011 at 9:39 AM, Francesco Nutini <nutini.france...@gmail.com> wrote: > > 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. >> > > > [[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. > -- Dimitri Liakhovitski Ninah Consulting www.ninah.com ______________________________________________ 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.