[R] R² for non-linear model + comparing linear + non-linear models

[Anna Gretschel]

Dear Bert,

so what can I do to obtain a goodness of fit for a non-linear model if 
r² does not work?

And here comes my next question: is it apropriate to comopare a linear 
and a non-linear model with anova()?

Thank you so much for answering,
Anna



Am 16.03.2011 18:54, schrieb Bert Gunter:
> Is there any way that this could be made into a fortune -- perhaps by
> omitting the poster's identity?
>
> "yes there are threads concidering this topic but they are all about the
> theory not about how to get the value of r^2 for a non-linear model in R."
>
> :=)
>
> Cheers,
> Bert
>
> Anna: I say this because you have just been told that the "theory"
> tells you that you CANNOT calculate R^2 for a nonlinear model.
>
>
> On Wed, Mar 16, 2011 at 10:25 AM, Anna Gretschel<ana-lee at web.de>  wrote:
>> Am 16.03.2011 18:15, schrieb David Winsemius:
>>> On Mar 16, 2011, at 12:53 PM, Anna Gretschel wrote:
>>>
>>>> Dear List,
>>>>
>>>> how can I obtain the value of r suqared for a non-linear model? For
>>>> linear models it can be found in the summary() of the model but for
>>>> non-linear models I just don't know. Please help!
>>> You should do more searching. I can remember at least two threads in the
>>> last few years that discussed this issue.
>>>
>> yes there are threads concidering this topic but they are all about the
>> theory not about how to get the value of r^2 for a non-linear model in R.
>>
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>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>