[R] Fitting exponential curve to data points

Stephen Tucker brown_emu at yahoo.com
Sat Jul 28 11:46:27 CEST 2007


Sorry, just got back into town.

I wonder if AIC, BIC, or cross-validation scoring couldn't also be used as
criteria for model selection - I've seen it mostly in the context of variable
selection rather than 'form' selection but in principle might apply here?


--- Dieter Menne <dieter.menne at menne-biomed.de> wrote:

> Andrew Clegg <andrew.clegg <at> gmail.com> writes:
> 
> > 
> > ... If I want to demonstrate that a non-linear curve fits
> > better than an exponential, what's the best measure for that? Given
> > that neither of nls() or optim() provide R-squared. 
> 
> To supplement Karl's comment, try Douglas Bates' (author of nls) comments
> on the
> matter
> 
> http://www.ens.gu.edu.au/ROBERTK/R/HELP/00B/0399.HTML
> 
> Short summary:
>     * ... "the lack of automatic ANOVA, R^2 and adj. R^2 from nls is a
> feature,
> not a bug :-)"
>     * My best advice regarding R^2 statistics with nonlinear models is, as
> Nancy
> Reagan suggested, "Just say no."
> 
> Dieter
> 
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