From: Guo Wei-Wei <wwguocn_at_gmail.com>

Date: Wed 12 Jul 2006 - 11:37:06 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 Jul 12 11:43:32 2006

Date: Wed 12 Jul 2006 - 11:37:06 EST

Than you, Gavin. You helped me out a lot of problems.

Thank you very much!

Wei-Wei

2006/7/12, Gavin Simpson <gavin.simpson@ucl.ac.uk>:

> On Wed, 2006-07-12 at 00:51 +0800, Guo Wei-Wei wrote:

*> > 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
**>
**> The scale of dist - they are just the differences between observed dist
**> and fitted dist (based on speed).
**>
**> mod <- lm(dist ~ speed, data = cars)
**> resid(mod)
**>
**> 1 2 3 4 5
**> 3.849460 11.849460 -5.947766 12.052234 2.119825
**> 6 7 8 9 10
**> -7.812584 -3.744993 4.255007 12.255007 -8.677401
**> ....
**>
**> # visualise the residuals
**> plot(resid(mod) ~ dist, data = cars)
**> abline(h = 0, col = "grey")
**> ## length of blue line represents the residual
**> lines(cars$dist, resid(mod), type = "h", col = "blue")
**>
**> So you see that for the 1st residual it is 3.849 ft (the distances are
**> measured in feet, see ?cars)
**>
**> Does this help?
**>
**> G
**>
**> >
**> >
**> > 2006/7/12, Gavin Simpson <gavin.simpson@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
**> > > --
**> > > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
**> > > Gavin Simpson [t] +44 (0)20 7679 0522
**> > > ECRC & ENSIS, UCL Geography, [f] +44 (0)20 7679 0565
**> > > Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk
**> > > Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/cv/
**> > > London, UK. WC1E 6BT. [w] http://www.ucl.ac.uk/~ucfagls/
**> > > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
**> > >
**> > >
**> >
**> > ______________________________________________
**> > 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
**> --
**> %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
**> Gavin Simpson [t] +44 (0)20 7679 0522
**> ECRC & ENSIS, UCL Geography, [f] +44 (0)20 7679 0565
**> Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk
**> Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/cv/
**> London, UK. WC1E 6BT. [w] http://www.ucl.ac.uk/~ucfagls/
**> %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
**>
**>
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