Ah, thank you very much - I did not understand first brglm was the name of a package! Dimitri
On Tue, Oct 1, 2013 at 11:34 AM, Xochitl CORMON <xochitl.cor...@ifremer.fr>wrote: > > > > <>< <>< <>< <>< > > Xochitl CORMON > > Le 01/10/2013 17:29, Dimitri Liakhovitski a écrit : > >> Thank you very much, Bert - it's very helpful. >> This post says that R issues a warning: >> >> Warning message: >> *glm.fit: fitted probabilities numerically 0 or 1 occurred >> * >> > > Actually the warning message should be something like: > glm.fit: algorithm did not converge > > The fist warning is not fatal contrary to the second one.. ( > https://stat.ethz.ch/**pipermail/r-help/2012-March/**307352.html<https://stat.ethz.ch/pipermail/r-help/2012-March/307352.html> > ) > > > However, in my case there is no warning. How could I detect complete >> separation in my data? I need to be able to flag it in my function. >> > > As said use the separation dectection function: separation.detection{brglm} > > Thank you very much! >> Dimitri >> >> >> >> On Tue, Oct 1, 2013 at 10:52 AM, Xochitl CORMON >> <xochitl.cor...@ifremer.fr >> <mailto:Xochitl.Cormon@**ifremer.fr<xochitl.cor...@ifremer.fr>>> >> wrote: >> >> Hi, >> >> I did have warning messages about convergence issues using binomial >> GLM with logit link with my data in the past.... >> >> Do you detect separation using the function >> separation.detection{brglm}? >> >> Regards, >> >> Xochitl C. >> >> >> <>< <>< <>< <>< >> >> Xochitl CORMON >> +33 (0)3 21 99 56 84 <tel:%2B33%20%280%293%2021%**2099%2056%2084> >> >> >> Doctorante en sciences halieutiques >> PhD student in fishery sciences >> >> <>< <>< <>< <>< >> >> IFREMER >> Centre Manche Mer du Nord >> 150 quai Gambetta >> 62200 Boulogne-sur-Mer >> >> <>< <>< <>< <>< >> >> >> >> Le 01/10/2013 16:41, Dimitri Liakhovitski a écrit : >> >> I have this weird data set with 2 predictors and one dependent >> variable - >> attached. >> >> predictor1 has all zeros except for one 1. >> I am runnning a simple logistic regression: >> >> temp<-read.csv("x data for reg224.csv") >> myreg<- glm(dv~predictor1+predictor2,_**_data=temp, >> >> family=binomial("logit")) >> myreg$coef2 >> >> Everything runs fine and I get the coefficients - and the fact >> that there >> is only one 1 on one of the predictors doesn't seem to cause any >> problems. >> >> However, when I run the same regression in SAS, I get warnings: >> Model Convergence Status Quasi-complete separation of data >> points >> detected. >> >> Warning: The maximum likelihood estimate may not exist. >> Warning: The LOGISTIC procedure continues in spite of the above >> warning. >> Results shown are based on the last maximum likelihood >> iteration. Validity >> of the model fit is questionable. >> >> And the coefficients SAS produces are quite different from mine. >> >> I know I'll probably get screamed at because it's not a pure R >> question - >> but any idea why R is not giving me any warnings in such a >> situation? >> Does it have no problems with ML estimation in this case? >> >> Thanks a lot! >> >> >> >> >> >> ______________________________**__________________ >> R-help@r-project.org <mailto:R-help@r-project.org> mailing list >> >> https://stat.ethz.ch/mailman/_**_listinfo/r-help<https://stat.ethz.ch/mailman/__listinfo/r-help> >> >> >> <https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help> >> > >> PLEASE do read the posting guide >> >> http://www.R-project.org/__**posting-guide.html<http://www.R-project.org/__posting-guide.html> >> >> >> <http://www.R-project.org/**posting-guide.html<http://www.R-project.org/posting-guide.html> >> > >> and provide commented, minimal, self-contained, reproducible code. >> >> >> ______________________________**__________________ >> R-help@r-project.org <mailto:R-help@r-project.org> mailing list >> >> https://stat.ethz.ch/mailman/_**_listinfo/r-help<https://stat.ethz.ch/mailman/__listinfo/r-help> >> >> >> <https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help> >> > >> PLEASE do read the posting guide >> >> http://www.R-project.org/__**posting-guide.html<http://www.R-project.org/__posting-guide.html> >> >> >> <http://www.R-project.org/**posting-guide.html<http://www.R-project.org/posting-guide.html> >> > >> and provide commented, minimal, self-contained, reproducible code. >> >> >> >> >> -- >> Dimitri Liakhovitski >> > -- Dimitri Liakhovitski [[alternative HTML version deleted]]
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