From: Gabor Grothendieck <ggrothendieck_at_gmail.com>

Date: Wed 15 Jun 2005 - 07:59:37 EST

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 Received on Wed Jun 15 08:20:43 2005

Date: Wed 15 Jun 2005 - 07:59:37 EST

On 6/14/05, Ajay Narottam Shah <ajayshah@mayin.org> wrote:

> I have a program which is doing a few thousand runs of lm(). Suppose

*> it is a simple model
**> y = a + bx1 + cx2 + e
**>
**> I have the R object "d" where
**> d <- summary(lm(y ~ x1 + x2))
**>
**> I would like to obtain Var(x2) out of "d". How might I do it?
**>
**> I can, of course, always do sd(x2). But it would be much more
**> convenient if I could snoop around the contents of summary.lm and
**> extract Var() out of it. I couldn't readily see how. Would you know
**> what would click?
**>
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Is the question how to get the variance of a column of the model matrix for a model that is the sum of terms given only summary output and the column name but not the name of the data frame? If that is it then try this:

d <- summary(lm(Sepal.Length ~ Sepal.Width, iris)) # test data var(model.matrix(eval(d$call))[,"Sepal.Width"])

If that's not the question, try examining the contents of d using

str(d)

and examine the output of lm via

str(eval(d$call))

and perhaps that will suggest the answer.

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 Received on Wed Jun 15 08:20:43 2005

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