It's due to the different coding of contrasts. Post to R-sig-mixed models for a fuller explanation (though it has nothing to do with mixed models; the same would happen with lm) or search on a suitable phrase (e.g. contrast coding in SAS versus R) in R archives or via google etc.
-- Bert On Mon, Nov 12, 2012 at 6:40 AM, Sophie GUERIN <s.gue...@has-sante.fr> wrote: > Hi, > > I am trying to fit a model with lmer in R and proc glimmix in SAS. I have > simplified my code but I am surprised to see I get different results from > the two softwares. > > My R code is : > lmer(y~age_cat + (1|cat),data=fic,family=binomial(link = "logit"), NaGQ=1) > > My SAS code is : > ods output Glimmix.Glimmix.ParameterEstimates=t_estimates; > proc glimmix data=tab_psi method=laplace; > class age_cat cat; > model psi (event='1') = age_cat / solution dist=B link=logit ; > random intercept / subject=cat; > run; > > >From R, I get the following fixed effects > (Intercept) age_cat2. 76-85 ans age_cat3. 66-75 ans age_cat4. 41-65 ans > -3.5766898 -0.0159466 -0.1919500 -0.4834741 > age_cat5. 18-40 ans > -1.2843977 > > But from SAS I get : > Valeur Erreur Valeur > Effet age_cat estimée type DDL du > test t Pr > |t| > > Intercept -4.8608 0.2859 3 -17.00 > 0.0004 > age_cat 1. >85-108 a 1.2841 0.2589 168E3 4.96 > <.0001 > age_cat 2. 76-85 ans 1.2681 0.2528 168E3 5.02 > <.0001 > age_cat 3. 66-75 ans 1.0921 0.2529 168E3 4.32 > <.0001 > age_cat 4. 41-65 ans 0.8006 0.2535 168E3 3.16 > 0.0016 > age_cat 5. 18-40 ans 0 . . . > . > > Even the intercept is different, but I can't find why. Has anyone an idea? > > Thanks in advance, > > Sophie > [[alternative HTML version deleted]] > > > ______________________________________________ > 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. > -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.
