[R] Obtaining values of estimates from a regression; How do I get values from a list?

[Ivan Calandra]

I find that the str() function is really helpful to understand how an object is
structured, and therefore how to extract part(s) of it.

Try for example:
str(zz)
and it might help you understand why zz$coefficients[2,1] is what you were
looking for.

HTH
Ivan

--
Dr. Ivan Calandra
TraCEr, laboratory for Traceology and Controlled Experiments
MONREPOS Archaeological Research Centre and
Museum for Human Behavioural Evolution
Schloss Monrepos
56567 Neuwied, Germany
+49 (0) 2631 9772-243
https://www.researchgate.net/profile/Ivan_Calandra

On February 22, 2019 at 8:50 AM Eric Berger <ericjberger using gmail.com> wrote:
> You have some choices
>
> fitchange$coefficients[2]
>
> zz$coefficients[2,1]
>
> Note that class(zz$coefficients) shows that it is a matrix.
>
> HTH,
> Eric
>
>
> On Fri, Feb 22, 2019 at 9:45 AM Sorkin, John <jsorkin using som.umaryland.edu>
> wrote:
>
> > I am trying to obtain the coefficients from a regression (performed using
> > lm). I would like to get the value for the slope (i.e. estimate) for pre
> > from the following regression:
> >
> >
> > fitchange <- lm(post-pre~pre,data=mydata2)
> >
> >
> > I have tried the following without any success:
> >
> >
> > zz <- summary(fitchange)["coefficients"]
> > class(zz)
> > print(zz)
> > zz[[2,1]]
> > zz[2,1]
> > zz["pre","Estimate"]
> >
> >
> > I clearly don't know how to select elements from the list returned by the
> > summary function.
> >
> >
> > A reproducible version of my code follows:
> >
> >
> > mydata2 <-structure(list(pre = c(71.3302299440613, 86.2703384845455,
> > 120.941698468568,
> > 80.9020778388552, 84.9927752038908,
> > 77.9108032451793, 111.007107108483,
> > 93.288442414475, 126.097826796255,
> > 111.63734644637),
> > post = c(45.9294556667686,
> > 114.661937978585, 138.501558726477,
> > 55.355775963925, 97.7906200355594,
> > 71.1008233796004, 149.308274695789,
> > 122.828428213951, 143.690814568562,
> > 116.607579975539)), class = "data.frame",
> > row.names = c(NA, -10L))
> >
> > fitchange <- lm(post-pre~pre,data=mydata2)
> > zz <- summary(fitchange)["coefficients"]
> > class(zz)
> > print(zz)
> > zz[[2,1]]
> > zz[2,1]
> > zz["pre","Estimate"]
> >
> >
> > Any help you can offer would be appreciated.
> >
> >
> >
> >
> >
> >
> > John David Sorkin M.D., Ph.D.
> > Professor of Medicine
> > Chief, Biostatistics and Informatics
> > University of Maryland School of Medicine Division of Gerontology and
> > Geriatric Medicine
> > Baltimore VA Medical Center
> > 10 North Greene Street
> > GRECC (BT/18/GR)
> > Baltimore, MD 21201-1524
> > (Phone) 410-605-7119
> > (Fax) 410-605-7913 (Please call phone number above prior to faxing)
> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > 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 using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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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