[R] Re gression for levels of a factor/xyplot type="r"

[Gabor Grothendieck]

See lmList in the lme4 package.  Each component of the result will be
one lm and you can take a summary of each.

On Wed, Sep 30, 2009 at 11:10 PM, jimdare <jamesdare26 at gmail.com> wrote:
>
> Hi,
>
> I'm sure these are basic problems so I apologise in advance for my
> ignorance.  I have a dataset with X, Y, and a Factor with 4 levels.  I am
> trying to figure out how to use lm() to find the r2 value, slope and
> intercept of an X~Y regression, for each level of the Factor.  Is there a
> way to do this automatically without having to specify different subsets of
> the factor?
>
> my code so far:
>
> Regression<-lm(Y~X, data=dataset, subset=factor(Factor))
>
> Also, when I plot this dataset using:
>
> xyplot(Y~X|factor(Factor), data=dataset, aspect="iso",
> type=c("p","g","r"),pch=21,cex=1)
>
> I get a four panel plot (one for each level of the factor) with a regression
> line for each.  How do I figure out the r2 value and coefficients of each
> regression line and add them as text to the plot.
>
> Thanks for your help!
>
> James
>
>
>
> --
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