[R] R² in a non-linear regresion analisys

[Karl Ove Hufthammer]

Douglas Bates:

> It may seem "obvious" how to define the multiple correlation
> coefficient R^2 for a non-linear regression model but it's not.

A couple of articles explaining why, that may be of interest:

Anderson-Sprecher R. (1994). ‘Model comparisons and R²’. The American
  Statistician, volume 48, no. 2, pages 113–117.
  http://dx.doi.org/10.2307/2684259

Kvålseth T.O. (1985). ‘Cautionary note about R²’. The American
  Statistician, volume 39, no. 4, pages 279–285.
  http://dx.doi.org/10.2307/2683704

-- 
Karl Ove Hufthammer