On Sep 13, 2011, at 9:34 AM, Jean-Christophe BOUËTTÉ wrote:
And you can easily get these predictions using the following code :
A <- B
I had a similar thought in that: resA_B <- A - B .... would give the
"residuals" from a line through the origin with a slope of 1. No
regression needed.
--
David
;-)
JC
2011/9/13 John Fox <j...@mcmaster.ca>:
Dear Ross,
lm(y ~ 0 + offset(x)) will do the trick, but the resulting model
has no
coefficient estimates and thus can't be used with abline(). You
can, e.g.,
get predictions from the model, but I'm not sure what real use it
will be to
you.
I hope this helps,
John
--------------------------------
John Fox
Senator William McMaster
Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-bounces@r-
project.org] On Behalf Of RCulloch
Sent: September-13-11 7:03 AM
To: r-help@r-project.org
Subject: [R] Force regression line to a 1:1 relationship
Hello,
I appreciate this is likely to be an easy question. I am trying to
obtain the residuals from a linear regression where the line is
forced
to have a
1:1 relationship.
An example of the data:
A<-c(0.9803922, 1.3850416, 0.8241758, 0.0000000, 0.4672897,
1.1904762,
0.0000000, 0.9456265,
1.5151515)
B<-c(1.3229572, 1.9471488, 1.3182674, 0.7007708, 1.0185740,
1.0268562,
0.8695652, 0.3016591, 1.9667171)
plot(A, B, ylim=c(0,2), xlim=c(0,2))
abline(0,1, col="lightgrey", lty="dashed",lwd=2)#1:1 relationship =
what I want to use in the lm()
#Normal regression
AB<-lm(A~B)
#plot regression line
abline(lm(AB))
How can I force the regression to have a 1:1 relationship, I
assume it
is to do with offset() but I have somewhat fried my brain trying
numerous variations and I am not convinced any are correct. I was
also
hoping the plot function would show me that the calculation is
correct,
but any time I use the offset() command there is no line plotted?
Any hints or tips would be much appreciated!
Ross
--
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regression-line-to-a-1-1-relationship-tp3809733p3809733.html
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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David Winsemius, MD
West Hartford, CT
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