[R] Force regression line to a 1:1 relationship

[David Winsemius]

On Sep 13, 2011, at 11:44 AM, David Winsemius wrote:

>
> On Sep 13, 2011, at 9:43 AM, RCulloch wrote:
>
>> Dear John,
>>
>> Thank you for that, and for explaining why the abline() command  
>> wont/dosen't
>> work. The approach is based on reviewers comments that I am a tad  
>> sceptical
>> about myself but yet curious enough to test their suggestion......I  
>> don't
>> think it is very straightforward to explain; however, it involves  
>> using the
>> residuals of the lm() and plotting them against a covariate to assess
>> whether or not the deviation from the 1:1 relationship is in someway
>> influenced by the other covariate. I hope that shines a small  
>> amount of
>> light on this rather unorthodox approach?!
>
> Plotting the residuals against a covariate is a standard way to  
> assess the assumption that the residuals are distributed normally  
> around each continuous regressor and have no non-linear relationship  
> around each continuous regressor
Forgot to include homoschedasticity:

   ...and have a reasonably constant standard deviation across the  
range of the regressor...

> . It is not to assess a "1:1 relationship", whatever that is. I  
> think we would need to  see a complete quotation of the reviewer's  
> comments before deciding who is confused in this interchange.
>
> -- 
> David Winsemius, MD
> West Hartford, CT
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT