Dear Suresh, The gnm package for generalized nonlinear models might be what you want here. This allows you to specify nonlinear models with family=quasipoisson.
For an introduction to the package see the article in R News: http://cran.r-project.org/doc/Rnews/Rnews_2007-2.pdf If your model requires a custom "nonlin" function and you get stuck on this, or you have any other queries about the package, I'm happy to be contacted directly. Best regards, Heather On 06/07/10 07:04, Suresh Krishna wrote: > > Hello R-helpers, > > I would like to fit a non-linear function to data (Discrete X axis, > over-dispersed Poisson values on the Y axis). > > I found the functions gnlr in the gnlm package from Jim Lindsey: this > can handle nonlinear regression equations for the parameters of Poisson > and negative binomial distributions, among others. I also found the > function nls2 in the software package accompanying the book "Statistical > tools for nonlinear regression" by Huet et al: this can handle nonlinear > regression with Poisson distributed Y-axis values. > > I was wondering if there was any other option: specifically, any option > that handled nonlinear fitting with quasi-Poisson distributions (to > handle the overdispersion). > > This is a very new area for me, and I am still trying to figure out the > best way to do this, so I would appreciate any and all pointers. > > Thanks much, Suresh > > ______________________________________________ > R-help@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@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.
