The Predict.Plot function in the TeachingDemos package can help you visualize interactions. It will work best if Month is treated as a continuous variable.
-- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.s...@imail.org 801.408.8111 > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of gaiarrido > Sent: Wednesday, August 17, 2011 2:57 AM > To: r-help@r-project.org > Subject: [R] interpreting interactions in a model > > Hi, > I´ve got this model > > model<-glm(prevalence~agesex+agesex:month,binomial) > > and the output of anova is like that > > > anova(model,test="Chisq") > Df Deviance Resid. Df Resid. Dev P(>|Chi|) > NULL 524 206.97 > agesex 2 9.9165 522 197.05 0.007025 ** > agesex:month 9 18.0899 513 178.96 0.034145 * > > I don´t know how to interpret the interaction "agesex:month", my mind > doubt > between 2 options: > a) For a giving group of "agesex" there are differences between months > b)There are differences between groups of "agesex" in some months but > not in > others. > > Which option is correct? > Thanks very much > > ----- > Mario Garrido Escudero > PhD student > Dpto. de Biología Animal, Ecología, Parasitología, Edafología y Qca. > Agrícola > Universidad de Salamanca > -- > View this message in context: > http://r.789695.n4.nabble.com/interpreting-interactions-in-a-model- > tp3749430p3749430.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. ______________________________________________ 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.
