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

[David Winsemius]

  This mostly seemed like a condensation of what had been said  
before ... threads from the past which were readily available through  
searching.

http://finzi.psych.upenn.edu/R/Rhelp02/archive/20370.html
http://finzi.psych.upenn.edu/R/Rhelp02/archive/73750.html
http://finzi.psych.upenn.edu/R/Rhelp02/archive/90168.html

install.packages("fortunes"); library(fortunes); fortune("curious")

http://finzi.psych.upenn.edu/Rhelp10/2009-April/196676.html
https://stat.ethz.ch/pipermail/r-help/2002-July/023461.html
http://finzi.psych.upenn.edu/R/Rhelp02/archive/35450.html

-- 
David.


On Mar 16, 2011, at 2:33 PM, Anna Gretschel wrote:

> Am 16.03.2011 19:29, schrieb Heiman, Thomas J.:
>> Hi Anna,
>>
>> AIC and BIC are good criteria for determining degree of model fit..
>>
>> Sincerely,
>>
>> tom
>>
>> Thomas Heiman, PhD
>> Info Systems Eng, Sr
>> The MITRE Corporation | Center for Enterprise Modernization
>> Office: 703-983-2951 | theiman at mitre.org
>>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org 
>> ] On Behalf Of Anna Gretschel
>> Sent: Wednesday, March 16, 2011 2:09 PM
>> To: Bert Gunter
>> Cc: r-help at r-project.org
>> Subject: Re: [R] R² for non-linear model + comparing linear + non- 
>> linear models
>>
>> 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.
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
> Thank you so much! Anna
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT