[R] Coefficient of Determination for nonlinear function

[Dieter Menne]

Uwe Wolfram wrote:
> 
> 
> I did fit an equation of the form 1 = f(x1,x2,x3) using a minimization
> scheme. Now I want to compute the coefficient of determination. Normally
> I would compute it as
> 
> r_square = 1- sserr/sstot with sserr = sum_i (y_i - f_i) and sstot =
> sum_i (y_i - mean(y))
> 
> sserr is clear to me but how can I compute sstot when there is no such
> thing than differing y_i. These are all one. Thus mean(y)=1. Therefore,
> sstot is 0. 
> 
> 

Try 

http://r-project.markmail.org/search/?q=r+square+nonlinear

to find heated debates on this subject. But I fear you supervisor or the
reviewer wants it anyway.

Dieter



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