Hi, I am quite new to R and would like to do nonlinear regressions with Poisson distributed data. I would like to estimate paramters of an equation of this type: FR = [c*NO * exp(a+b*NO)] / [(c+NO)*(1+exp(a+b*NO))] a,b and c are parameters, NO are input values I found both the gnm and gnlr3 function which should be able to do this regression but I can't manage to make it work. How can I write my equation to fit into these functions? If I understand it correct I have to split my equation in a "mu", a "shape" and a "family" part for the gnlr function, but don't have a clue how to do this..................... Is there maybe a different function that is better for my purpose? A version of nls where I can choose a different distribution? 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.audenaert@pcsierteelt.be www.pcsierteelt.be ______________________________________ [[alternative HTML version deleted]]