Just to clarify things before trying to answer: by a "1:1 relationship" do
you mean you want the regression slope to be equal to 1 "no matter what"?

Michael

On Tue, Sep 13, 2011 at 7:03 AM, RCulloch <ross.culloch@dur.ac.uk> wrote:

> 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
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Force-regression-line-to-a-1-1-relationship-tp3809733p3809733.html
> Sent from the R help mailing list archive at Nabble.com.
>
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