On Tue, 2008-04-22 at 17:04 +0200, [EMAIL PROTECTED] wrote: > Hi Robert, > > you can exclude the intercept by including "-1" in the formula: > > value <- as.numeric(runif(20)<.4) > ppm <- rnorm(20) > glm(value~ppm-1,family=binomial)
Note that 0+ppm is the same thing, try it: glm(value ~ 0 + ppm, family=binomial) Your approach and that of Robert's are two ways to skin that particular cat. G > > HTH > Stephan > > > > Dear Statisticians, > > > > I would like to analyse my data with a GLM with binomial error distribution > > and logit link function. The point is that I want a model fitted without > > intercept, i.e. the fitted curve should start at y=0.5 for x=0. > > > > I tried it with the following code: > > > > glm(value~0+ppm, binomial) > > > > Does this code yield the correct model or is there another possibility? I?d > > appreciate it very much if you could help me out with this. I attached some > > example data. > > > > Thanks & all the best > > > > Robert > > -- > > ______________________________________________ > 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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ 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.
