There is a bug in your code: Try reg2<-predict.glm(reg1, se.fit=T, data.frame(male=1, edu=1, married=1,inc=1, relig=1, YEAR=seq(1,33,1)), type="response")
You put type="response" into your newdata frame, so it wasn't visible to predict.glm. So predict.glm assumed the default type, which is "link". Cheers, Simon. On Sun, 2009-03-08 at 23:39 -0700, Kitty Lee wrote: > I have a puzzle.... > > When I include an interaction in the model, many predicted probabilities are > above 1. Is that a problem with my model? I thought the predicted prob can't > be bigger than 1... > > Any help would be really appreciated! Thanks! > > K. > > reg1<-glm(pyea~male+edu+married+inc+relig+factor(time)+ > factor(time)*male, data=mydata, family=binomial(link="logit")) > > reg2<-predict.glm(reg1, se.fit=T, data.frame(male=1, edu=1, married=1,inc=1, > relig=1, type='response', YEAR=seq(1,33,1)) > > reg2$fit > > $fit > 1 2 3 4 5 6 7 > 8 9 10 11 > 0.6105101 0.5249279 0.4717028 0.5525786 0.5622492 0.3387205 0.3010051 > 0.5836462 0.6478388 0.9158862 0.9849557 > 12 13 14 15 16 17 18 > 19 20 21 22 > 1.1208788 1.1440165 1.2053129 1.0169487 1.1832429 1.4162309 1.0612279 > 1.2038962 1.1274700 1.0876280 0.9704570 > 23 24 25 26 27 28 29 > 30 31 32 33 > 1.0160205 1.0410419 0.9526990 1.0043029 1.1337670 1.2502910 0.9927158 > 1.0924190 0.8315262 1.0530386 1.5727090 > > ______________________________________________ > 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. -- Simon Blomberg, BSc (Hons), PhD, MAppStat. Lecturer and Consultant Statistician School of Biological Sciences The University of Queensland St. Lucia Queensland 4072 Australia Room 320 Goddard Building (8) T: +61 7 3365 2506 http://www.uq.edu.au/~uqsblomb email: S.Blomberg1_at_uq.edu.au Policies: 1. I will NOT analyse your data for you. 2. Your deadline is your problem. The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. - John Tukey. ______________________________________________ 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.
