On Oct 23, 2012, at 1:43 PM, hoguejm <hogu...@gmail.com> wrote: > I have a rather large data set (about 30 predictor variables) > > I need to preform a logistic regression on this data. My response variable > is binary. > > My code looks like this: > > mylogit <- glm(Enrolled ~ A + B + C + ... + EE, data = data, family = > binomial(link="logit")) > > with A,B,C, ... as my predictor variables. Some categorical, some > continuous, some binary. > > I run the code and get this error: > > Error in `contrasts<-`(`*tmp*`, value = contr.funs[1 + isOF[nn]]) : > contrasts can be applied only to factors with 2 or more levels > > Any ideas on how to fix this? I am fairly new to R so Im guessing there is > something missing/wrong in my logit code. > > Thanks!
More than likely, one or more of your categorical variables are not set up as factors, or if they are, then one or more have only a single factor level present in the dataset that is used for the model, thus are constant. You might want to run: # see ?str str(data) and: # see ?summary summary(data) to get a sense of the structure of your data set (to make sure that you have factors and not character vectors) and to get a sense for the distribution of your IVs. Regards, Marc Schwartz ______________________________________________ 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.
