[R] Question on partial effect

[Guo Wei-Wei]

Thank you, Gavin. I think that might be what I need. But I'm a little
bit wandering what's the scale of resid(mod). Is it
scale(dist)/scale(speed), for example kilometer / (kilometer per
hour)? or something else?

Thank you very much!
Wei-Wei


2006/7/12, Gavin Simpson <gavin.simpson at ucl.ac.uk>:
> On Tue, 2006-07-11 at 23:51 +0800, Guo Wei-Wei wrote:
> > Dear all,
> >
> > I don't know what's my question is called. I have a performance
> > variable A, such as sales. And I have another variable B, let's say
> > establish time of firm. I want to create the third variable that is
> > sales without the effect of establish time. Maybe it can be called
> > partial effect problem. I'm not sure.
> >
> > Does anyone have any suggestion? Thank you in advance!
> >
> > All the best,
> > Wei-Wei
>
> Do you mean?
>
> ## dummy data
> A <- rnorm(100)
> B <- rnorm(100)
> C <- resid(lm(A ~ B))
>
> C now contains the residual variation in A after fitting B.
>
> e.g. with some real data
> ?cars
> data(cars) # not sure this is needed now, I forget
> mod <- lm(dist ~ speed, data  = cars)
> summary(mod)
> partial <- resid(mod)
>
> ## check
> mod2 <- lm(dist ~ partial, data = cars)
> summary(mod2)
> ## from the two R^2 form mod1 and mod2 - partial contains dist minus
> ## the effects of speed
> > 0.6511 + 0.3489
> [1] 1
>
> HTH
>
> G
> --
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>  Gavin Simpson                 [t] +44 (0)20 7679 0522
>  ECRC & ENSIS, UCL Geography,  [f] +44 (0)20 7679 0565
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