I think what you want is ?try ##or ?tryCatch
## The second is more flexible but slightly more complicated. to trap the error and perhaps refit the model without interaction? Cheers, Bert On Mon, Jul 15, 2013 at 10:45 AM, Hermann Norpois <hnorp...@gmail.com> wrote: > Hello, > > I use glm within a function testing for the appearence of the coexistence > of (minor allels in a subset of) snps. And then I extract the > Pr(>|z|)-value for the interaction. Principally it works but sometimes the > function stops because this "value for the interaction" is NA. For > instance, this is the case in the following example: > > lz <- glm(trait~rs7572685*rs10520302, data=mus, family=binomial) >> summary (lz) > ... > Coefficients: (1 not defined because of singularities) > Estimate Std. Error z value Pr(>|z|) > (Intercept) 0.05614 0.16782 0.335 0.738 > rs7572685 0.49041 0.41437 1.183 0.237 > rs10520302 0.49269 0.43514 1.132 0.258 > rs7572685:rs10520302 NA NA NA NA > ... > > I would prefer some values instead of NA (though it does not make any sense > in terms of interpretation) for the sake of the smooth running of my > function. How is this done? I guess I have to change the offset but I dont > understand how. > Thanks > > [[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. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.