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 <quantumeli...@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 <jsals...@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 >> jsals...@talknicer.com >> http://talknicer.com >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel > > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel