[Lme4-authors] AIC calculation
[forwarding to r-sig-mixed-models]
On 13-10-15 04:44 AM, Miguel Boubeta Mart?nez wrote:
Hello, The lastest versions were 0.999999-2 and 1.0-4. I fit a GLMM, as glmm=glmer(y~ x + (1|dd),family=poisson()) where 'y' is the response, 'x' is the covariate and 'dd' is the area. With these options, the AIC results were different. Could you give me the reference of the calculation of AIC used in lme4? Sincerely,z`` Miguel.
From the NEWS file for lme4, e.g.
news(grepl("consistent",Text) & Version=="1.0-0",package="lme4")
: As another side effect of matching glm behaviour, reported log-likelihoods from glmer models are no longer consistent with those from pre-1.0 lme4, but _are_ consistent with glm; see glmer examples. The AIC calculation (given the log-likelihood) is completely standard: it's the log-likelihood calculation you have to be careful about -- see lme4:::logLik.merMod (which also specifies the computation of the number of parameters). Ben Bolker z``>
------------------------------------------------------------------------ *De:* lme4 maintainer <bbolker at gmail.com> *Para:* Miguel Boubeta Mart?nez <miguel.boubeta at yahoo.es>; "lme4-authors at lists.r-forge.r-project.org" <lme4-authors at lists.r-forge.r-project.org> *Enviado:* Martes 15 de octubre de 2013 5:03 *Asunto:* Re: [Lme4-authors] AIC calculation Certainly not without a reproducible example, or at least a lot more details (what were the "latest versions", i.e. are you referring to versions 0.999x and 1.0x , or 1.0-4 and 1.1-0 ?) Was there anything else different about the fits (parameter values, log-likelihood)? Was this a GLMM or a LMM? etc etc etc. Our recommended advice is to send general questions first to r-sig-mixed-models at r-project.org <mailto:r-sig-mixed-models at r-project.org> , where someone else may be able to answer. Please read http://tinyurl.com/reproducible-000 on how to create good reproducible examples, and the posting guide for the R lists, first (google "R mailing list posting guide") sincerely Ben Bolker