Dear Terry, Does fitting group + age:group instead of age*group solves your problem?
Best regards, ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance Kliniekstraat 25 1070 Anderlecht Belgium To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner 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 2016-04-15 13:58 GMT+02:00 Therneau, Terry M., Ph.D. <thern...@mayo.edu>: > I'd like to get interaction terms in a model to be in another form. > Namely, suppose I had variables age and group, the latter a factor with > levels A, B, C, with age * group in the model. What I would like are the > variables "age:group=A", "age:group=B" and "age:group=C" (and group itself > of course). The coefficients of the model will then be the age effect in > group A, the age effect in group B and the age effect in C rather than the > standard ones of an overall age effect followed by contrasts. These is > often a better format for tables in a publication. > > Yes, I can reconstruct these from the original fit, but I have a lot of > variables for several models and it would be easier to have an automatic > form. I suspect that there is an easy answer, but I don't see it. > > Terry Therneau > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
