From jsalsman at talknicer.com  Mon Mar  8 06:00:27 2010
From: jsalsman at talknicer.com (James Salsman)
Date: Sun, 7 Mar 2010 21:00:27 -0800
Subject: [Rd] application to mentor syrfr package development for Google
	Summer of Code 2010
In-Reply-To: <7021740b1003071935p51d4ed7dq2fe481e499f0ef5@mail.gmail.com>
References: <a3c2bd6c1003071711h346dd79fr820a41f9080700fc@mail.gmail.com>
	<7021740b1003071935p51d4ed7dq2fe481e499f0ef5@mail.gmail.com>
Message-ID: <a3c2bd6c1003072100g2e9ff45fw69c45b9257fa6e5c@mail.gmail.com>

Chillu,

If I understand your concern, you want to lay the foundation for
derivatives so that you can implement the search strategies described
in Schmidt and Lipson (2010) --
http://www.springerlink.com/content/l79v2183725413w0/ -- is that
right? It is not clear to me how well this generalized approach will
work in practice, but there is no reason not to proceed in parallel to
establish a framework under which you could implement the metrics
proposed by Schmidt and Lipson in the contemplated syrfr package.

I have expanded the test I proposed with two more questions -- at
http://rwiki.sciviews.org/doku.php?id=developers:projects:gsoc2010:syrfr
-- specifically:

5. Critique http://sites.google.com/site/gptips4matlab/

6. Use anova to compare the goodness-of-fit of a SSfpl nls fit with a
linear model of your choice. How can your characterize the
degree-of-freedom-adjusted goodness of fit of nonlinear models?

I believe pairwise anova.nls is the optimal comparison for nonlinear
models, but there are several good choices for approximations,
including the residual standard error, which I believe can be adjusted
for degrees of freedom, as can the F statistic which TableCurve uses;
see: http://en.wikipedia.org/wiki/F-test#Regression_problems

Best regards,
James Salsman


On Sun, Mar 7, 2010 at 7:35 PM, Chidambaram Annamalai
<quantumelixir at gmail.com> wrote:
> It's been a while since I proposed syrfr and I have been constantly in
> contact with the many people in the R community and I wasn't able to find a
> mentor for the project. I later got interested in the Automatic
> Differentiation proposal (adinr) and, on consulting with a few others within
> the R community, I mailed John Nash (who proposed adinr in the first place)
> if he'd be willing to take me up on the project. I got a positive reply only
> a few hours ago and it was my mistake to have not removed the syrfr proposal
> in time from the wiki, as being listed under proposals looking for mentors.
>
> While I appreciate your interest in the syrfr proposal I am afraid my
> allegiances have shifted towards the adinr proposal, as I got convinced that
> it might interest a larger group of people and it has wider scope in
> general.
>
> I apologize for having caused this trouble.
>
> Best Regards,
> Chillu
>
> On Mon, Mar 8, 2010 at 6:41 AM, James Salsman <jsalsman at talknicer.com>
> wrote:
>>
>> Per http://rwiki.sciviews.org/doku.php?id=developers:projects:gsoc2010
>> -- and
>> http://rwiki.sciviews.org/doku.php?id=developers:projects:gsoc2010:syrfr
>> -- I am applying to mentor the "Symbolic Regression for R" (syrfr)
>> package for the Google Summer of Code 2010.
>>
>> I propose the following test which an applicant would have to pass in
>> order to qualify for the topic:
>>
>> 1. Describe each of the following terms as they relate to statistical
>> regression: categorical, periodic, modular, continuous, bimodal,
>> log-normal, logistic, Gompertz, and nonlinear.
>>
>> 2. Explain which parts of http://bit.ly/tablecurve were adopted in
>> SigmaPlot and which weren't.
>>
>> 3. Use the 'outliers' package to improve a regression fit maintaining
>> the correct extrapolation confidence intervals as are between those
>> with and without outlier exclusions in proportion to the confidence
>> that the outliers were reasonably excluded. ?(Show your R transcript.)
>>
>> 4. Explain the relationship between degrees of freedom and correlated
>> independent variables.
>>
>> Best regards,
>>
>> James Salsman
>> jsalsman at talknicer.com
>> http://talknicer.com
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>
>



[Rd] application to mentor syrfr package development for Google Summer of Code 2010
James Salsman