Hi Vasco, With only 20 observations, you probably need to simplify your model. The best you can really hope for is to estimate 2 parameters. First try dropping (1|Plot:Grazing).
The Tweedie distribution is also available now. Try family=tweedie(link = "log"). cheers, Mollie > On 17Feb 2018, at 5:54, Vasco Silva <silvadava...@gmail.com> wrote: > > Hi, > > I am trying to fit a GLMM on biomass for each individual species using > glmmTMB but I got the following warning messages. I start to model the > zeros in a binomial model and the non-zeros in Gamma. > >> str(biomass) > 'data.frame': 20 obs. of 15 variables: > $ Plot : Factor w/ 10 levels "P1","P10","P2",..: 1 3 4 5 6 7 8 9 > 10 2 ... > $ Grazing : Factor w/ 2 levels "Fenced","Unfenced": 1 1 1 1 1 1 1 1 > 1 1 ... > $ sp1 : num 247.61 10.9 0 24.92 2.14 ... > $ sp2 : num 244 0 0 2907 0 ... > $ sp3 : num 2147 2410 1030 1227 368 ... > $ sp3 : num 0 0 0 0 0 ... > > ## > m0<-glmmTMB(sp2.positive ~ Grazing+(1|Plot)+(1|Plot:Grazing), > data=biomass,family=binomial(link="logit")) > > $cond > Estimate Std. Error z value Pr(>|z|) > (Intercept) -1.386333 0.9845106 -1.408144 0.1590885 > GrazingUnfenced 2.233656 1.4343891 1.557218 0.1194188 > > $zi > NULL > > $disp > NULL > > > ## > m1<-glmmTMB(sp2~Grazing+(1|Plot)+(1|Plot:Grazing),data=biomass[biomass$sp2>0,], > > family=Gamma(link="log"),control=glmmTMBControl(optCtrl=list(iter.max=1e3,eval.max=1e3))) > > #Warning messages:1: In fitTMB(TMBStruc) : > Model convergence problem; extreme or very small eigen values > detected. See vignette('troubleshooting')2: In fitTMB(TMBStruc) : > Model convergence problem; false convergence (8). See > vignette('troubleshooting') > > > I check the vignette (troubleshooting) of the package but I canĀ“t fix the > problem. Should I (re)scale the data? I saw that Tweedie is not (yet) > implemented in glmmTMB ( > https://cran.r-project.org/web/packages/glmmTMB/vignettes/glmmTMB.pdf). Any > alternative for modeling zero-inflated continuous data? > > I would greatly appreciate it if someone could help me. > > Cheers. > > Vasco Silva > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-ecology mailing list > R-sig-ecology@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology