¿Just write down the loglikelihood function and send it to optim? Kjetil
On Tue, Apr 3, 2012 at 8:58 AM, Joachim Audenaert <joachim.audena...@pcsierteelt.be> wrote: > Hello all, > > I would like to get parameter estimates for different models. For one of > them I give the code in example. I am estimating the parameters (i,j and > k) with the nls function, which sees the error distribution as normal, I > would however like to do the same as nls with the assumption that the > errors are poisson distributed. > > Is there a way to do this with R? Are there packages designed for this? I > tried with the gnm package, but don't understand how to transform my > equation to a generalised equation. Is there an option for nls to choose > family = poisson? > > Lower in the mail the code with the model and visualisations I use to > check my results. I also copied the test dataset from my txt file. > > I am using R 2.15 and Rstudio to visualise it. > > > plot(FR~N0) > x <- > nls(FR~(exp(i+j*N0)/(1+exp(i+j*N0)))*(k*N0/(k+N0)),start=list(i=0.02,j=0.002,k=6)) > summary(x) > hatx <- predict(x) > lines(spline(N0,hatx)) > > N0 FR > 10 2 > 10 3 > 10 2 > 10 4 > 10 2 > 10 2 > 10 1 > 10 2 > 10 2 > 10 2 > 20 2 > 20 3 > 20 3 > 20 3 > 20 4 > 20 2 > 20 4 > 20 2 > 20 3 > 20 2 > 30 1 > 30 2 > 30 3 > 30 4 > 30 5 > 30 6 > 30 2 > 30 3 > 30 2 > 30 2 > 40 2 > 40 3 > 40 3 > 40 6 > 40 5 > 40 4 > 40 3 > 40 3 > 40 2 > 40 3 > 50 4 > 50 5 > 50 2 > 50 3 > 50 7 > 50 5 > 50 4 > 50 3 > 50 4 > 50 5 > 60 5 > 60 6 > 60 8 > 60 4 > 60 4 > 60 3 > 60 2 > 60 2 > 60 5 > 60 4 > > Kind Regards > Joachim > > Don't waste paper! Think about the environment before printing this e-mail > > ______________________________________ > > Joachim Audenaert > Adviesdienst Gewasbescherming > Proefcentrum voor Sierteelt > Schaessestraat 18 > B-9070 Destelbergen > Tel. +32 9 353 94 71 > Fax +32 9 353 94 95 > E-mail: joachim.audena...@pcsierteelt.be > www.pcsierteelt.be > ______________________________________ > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
