From: Francesco Nutini <nutini.francesco_at_gmail.com>

Date: Fri, 20 May 2011 17:45:10 +0200

R-help_at_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. Received on Fri 20 May 2011 - 23:06:03 GMT

Date: Fri, 20 May 2011 17:45:10 +0200

Please forgive me for all these questions Dimitri...

> Date: Fri, 20 May 2011 10:01:39 -0400

*> Subject: Re: [R] [r] regression coefficient for different factors
**> From: dimitri.liakhovitski_at_gmail.com
**> To: nutini.francesco_at_gmail.com
**> CC: rbaer_at_atsu.edu; r-help_at_r-project.org
**>
**> First you have to create something (e.g., a list) that holds your output:
**>
**> mylist<-NULL
**>
**> Then you loop through the levels of c and run a regression of a onto b
**> (no need to include c anymore because c will have zero variance within
**> each level of c):
**> for(i in levels(c)){
**> temp.data<-mydataset[mydataset$c %in% i]
**> mylist[[i]]<-lm(a ~ b, data=temp.data)
**> }
**>
**> Once you are done - you can write another loop (this time across all
**> elements of mylist - that will have as many elements as there are
**> levels in c) and extract the coefficients.
**> Dimitri
**>
**>
**> On Fri, May 20, 2011 at 9:57 AM, Francesco Nutini
**> <nutini.francesco_at_gmail.com> wrote:
**> > Yes Dimitri that's what I mean!
**> > Something like this?
**> >
**> > for(i in levels(c)) { lm(a ~ b * c , data=mydataset)}
**> >
**> > And what about to see the output?
**> >
**> > Thanks!
**> >
**> >> Date: Fri, 20 May 2011 09:46:08 -0400
**> >> Subject: Re: [R] [r] regression coefficient for different factors
**> >> From: dimitri.liakhovitski_at_gmail.com
**> >> To: nutini.francesco_at_gmail.com
**> >> CC: rbaer_at_atsu.edu; r-help_at_r-project.org
**> >>
**> >> 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.francesco_at_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: rbaer_at_atsu.edu
**> >> >> To: nutini.francesco_at_gmail.com; r-help_at_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.francesco_at_gmail.com>
**> >> >> Sent: Friday, May 20, 2011 4:17 AM
**> >> >> To: "[R] help" <r-help_at_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_at_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_at_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
**> >
**>
**>
**>
**> --
**> Dimitri Liakhovitski
**> Ninah Consulting
**> www.ninah.com
*

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