[R] se's and CI's for fitted lines in multivariate regression analysis

[Bert Gunter]

?predict

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-- Bert

On Wed, Oct 10, 2012 at 6:49 AM, Sigrid <s.stenerud at gmail.com> wrote:
> I’m entirely stumped on this particular issue and really hoping someone has
> some advice for me.
>
> I am running a covariant model in lm I would like to give the standard
> errors or the confidence intervals for the fitted lines. I’ve been using the
> dataset OrangeSprays where I want lines for each level of treatment over the
> covariant ‘colpos’. I’ve been able to calculate intercepts and slopes for
> each lines by adding up the parameters, but this does not make sense when
> the comes to the se’s.  I’ve run the summary (model) function, but only get
> the differences in standard error between lines. Also by running
> confint(model), I have the same problem.
>
> How can I get standard error per or the CI-interval for each fitted line?
> I’ve attached the coding underneath.
>
> Thank you,
> Sigrid
>
>> data(OrchardSprays)
>> model<-lm(decrease~rowpos+colpos+treatment+treatment:colpos)
>> summary(model)
>
>
>
>
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>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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