[R] Getting the R squared value in asymptotic regression model

[David Winsemius]

On Jan 12, 2013, at 3:30 PM, Ahmed Attia wrote:

> Please help getting the R squared value in asymptotic regression model
>
> I use the code below
>
> model1<-nls(GN1~SSasymp (nrate,a,b,c), data = data.1 )
>
> and R produced the modell coefficients without the R squared value?

What makes you think there should be an R^2 value?

 From the archives:
https://stat.ethz.ch/pipermail/r-help/2002-July/023461.html

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892436/

 From the background section to that article:

"Although it is known now for some time that R2 is an inadequate  
measure for nonlinear regression, many scientists and also reviewers  
insist on it being supplied in papers dealing with nonlinear data  
analysis. Several initial and older descriptions for R2 being of no  
avail in nonlinear fitting had pointed out this issue but have  
probably fallen into oblivion [2-8]. This observation might be due to  
differences in the mathematical background of trained statisticians  
and biochemists/pharmacologists who  often apply statistical methods  
but lack detailed statistical insight."

-- 

David Winsemius, MD
Alameda, CA, USA