Thanks a lot, Heather, >>>>> "HT" == Heather Turner <heather.tur...@warwick.ac.uk> >>>>> on Fri, 13 Feb 2009 11:49:06 +0000 writes:
HT> Dear Martin, HT> I think a simulate.glm method ought to be able to work for gnm objects HT> too. David Firth and I started to work on this a long time ago, but HT> stopped part-way through when simulate.lm was introduced, thinking that HT> simulate.glm was probably in the pipeline and we were duplicating HT> effort. Obviously we have let this slip when a contribution might have HT> been useful. We developed a prototype for poisson, binomial, gaussian, HT> gamma and inverse gaussian models which might be usefully merged with HT> Ben's proposed simulate.glm. What's the best way to go about this? I HT> would also like to test the proposed simulate.glm to check whether it HT> will work with gnm objects or whether a simulate.gnm will be necessary. In the mean time, private e-mail communications have started on the subject, and yes, we are very insterested in finding ``the best'' possible way, probably making use of Heather+David's code together with Ben's. One alternative (not mentioned yet on R-devel), we've been considering is to use simulate.lm() to also deal with "glm" (and possibly "gnm") objects ``in one place''. Martin HT> Martin Maechler wrote: >>>>>>> "BB" == Ben Bolker <bol...@ufl.edu> >>>>>>> on Thu, 12 Feb 2009 11:29:14 -0500 writes: >> BB> I have found the "simulate" method (incorporated BB> in some packages) very handy. As far as I can tell the BB> only class for which simulate is actually implemented BB> in base R is lm ... this is actually a little dangerous BB> for a naive user who might be tempted to try BB> simulate(X) where X is a glm fit instead, because BB> it defaults to simulate.lm (since glm inherits from BB> the lm class), and the answers make no sense ... >> BB> Here is my simulate.glm(), which is modeled on BB> simulate.lm . It implements simulation for poisson BB> and binomial (binary or non-binary) models, should BB> be easy to implement others if that seems necessary. >> BB> I hereby request comments and suggest that it wouldn't BB> hurt to incorporate it into base R ... (I will write BB> docs for it if necessary, perhaps by modifying ?simulate -- BB> there is no specific documentation for simulate.lm) >> BB> cheers BB> Ben Bolker >> >> [...............] >> >> Hi Ben, >> thank you for your proposals. >> >> I agree that simulate.glm() has been in missing in some way, >> till now, in particular, as, as you note, "glm" objects extend >> "lm" ones and hence simulate(<glm>, ...) currently dispatches to >> calling simulate.lm(....) which is only correct in the case of >> the gaussian family. >> >> I have looked at your proposal a bit, already "improved" the >> code slightly (e.g. re-include the comment you lost when you >> ``copied'' simulate.lm(): In such cases, please work from the >> source, not from what you get by print()ing >> stats:::simulate.lm --- the source is either a recent tarball, >> or the SVN repository, in this case, file >> https://svn.r-project.org/R/trunk/src/library/stats/R/lm.R ] >> and am planning to look at your and some own examples; >> all with the goal to indeed include this in the R standard >> 'stats' package in R-devel [to become R 2.9.0 in the future]. >> >> About the help page: At the moment, I think that only a few >> words would need to be added to the simulate help page, >> i.e., https://svn.r-project.org/R/trunk/src/library/stats/man/simulate.Rd >> and will be happy to receive a patch against this file. >> >> Thank you again, and best regards, >> Martin Maechler, ETH Zurich ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel