On 21-Mar-08 15:59:05, Alfonso Pérez wrote: > Hello, my name is Alfonso. I want to apply a logistic model to my data. > The variables are, fish length and age length as a continous variable, > and cohort as a factor. I consider the interaction between age and > cohort in the model. The dependent variable is the probability of being > mature. Then the model is as follow: > > ogive <- glm(mature~length+(cohort*age), family=binomial, > data=subset.cod) > > > But when I run it in R I obtain a Warning message: > > Warning message: > In glm.fit(x = X, y = Y, weights = weights, start = start, etastart = > etastart, : > fitted probabilities numerically 0 or 1 occurred > > I don't understand what's the problem, could you help me? thank you > in advance. > > Alfonso.
There was effectively the same question from Werner Wernersen: "[R] glm.fit: "fitted probabilities numerically 0 or 1 occurr" 11 March 2008 08:58:55. See my response to him: "Re: [R] glm.fit: "fitted probabilities numerically 0 or 1 occurr" From: (Ted Harding) <[EMAIL PROTECTED]> Date: Tue, 11 Mar 2008 10:08:09 -0000 (GMT) which covers the maun issues. The underlying reason is that some linear function of your covariates compeletly separates the "Y=1" cases from the "Y=0" cases, so the GLM can predict probability 1 for "Y=1", and probability 0 for "Y=0". Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 21-Mar-08 Time: 16:53:54 ------------------------------ XFMail ------------------------------ ______________________________________________ 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.
