Re: [R] Coefficient of Determination for nonlinear function

From: Dieter Menne <dieter.menne_at_menne-biomed.de>
Date: Fri, 04 Mar 2011 10:09:27 -0800 (PST)

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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Received on Fri 04 Mar 2011 - 18:12:48 GMT

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