Dear Douglas, Thank you for your reply. Just some extra info on the dataset: In my case Number of obs is 33, and number of groups of factor(Farm_code) is 12. This is the information on iterations I get:
summary(lmer(round(SR_SUN)~Dist_NV + (1|factor(Farm_code)) , family=poisson, verbose =TRUE)) 0: 60.054531: 1.06363 2.14672 -0.000683051 1: 60.054531: 1.06363 2.14672 -0.000683051 Error in asMethod(object) : matrix is not symmetric [1,2] In addition: Warning message: In mer_finalize(ans) : singular convergence (7) When I run a similar model (exp variable Dist_hives) the number of iterations is 11: summary(lmer(round(SR_SUN)~Dist_hives + (1|factor(Farm_code)) , family=poisson, verbose =TRUE)) 0: 61.745238: 0.984732 1.63769 0.000126484 1: 61.648229: 0.984731 1.63769 -2.08637e-05 2: 61.498777: 0.984598 1.63769 4.11867e-05 3: 47.960908: 0.381062 1.63585 6.77029e-05 4: 46.223789: 0.250732 1.66727 8.31854e-05 5: 46.222223: 0.250732 1.66727 6.97790e-05 6: 46.216710: 0.250730 1.66727 7.60560e-05 7: 46.168835: 0.230386 1.64883 9.16430e-05 8: 46.165955: 0.228062 1.65658 8.70694e-05 9: 46.165883: 0.228815 1.65737 8.63400e-05 10: 46.165883: 0.228772 1.65734 8.63698e-05 11: 46.165883: 0.228772 1.65734 8.63701e-05 I am very confused with the fact that it runs with Dist_hives and not with Dist_NV. Both variables are distance values, the first having no obvious relation with the response variable and the second (Dist_NV) seems to have a negative effect on SR_SUN. Does this information helps identifying the problem with my data/analysis? Thank you, Luisa On Tue, Feb 16, 2010 at 5:35 PM, Douglas Bates <ba...@stat.wisc.edu> wrote: > This is similar to another question on the list today. > > On Tue, Feb 16, 2010 at 4:39 AM, Luisa Carvalheiro > <lgcarvalhe...@gmail.com> wrote: >> Dear R users, >> >> I am having problems using package lme4. >> >> I am trying to analyse the effect of a continuous variable (Dist_NV) >> on a count data response variable (SR_SUN) using Poisson error >> distribution. However, when I run the model: >> >> summary(lmer((SR_SUN)~Dist_NV + (1|factor(Farm_code)) , >> family=poisson, REML=FALSE)) >> >> 1 error message and 1 warning message show up: >> >> in asMethod(object) : matrix is not symmetric [1,2] >> In addition: Warning message: >> In mer_finalize(ans) : singular convergence (7) > > So the first thing to do is to include the optional argument verbose = > TRUE in the call to lmer. (Also, REML = FALSE is ignored for > Generalized Linear Mixed Models and can be omitted. although there is > no harm in including it.) > > You need to know where the optimizer is taking the parameter values > before you can decide why. > > P.S. Questions like this will probably be more readily answered on the > R-SIG-Mixed-Models mailing list. > >> A model including Dist_NV together with other variables runs with no >> problems. >> What am I doing wrong? >> >> Thank you, >> >> Luisa >> >> >> -- >> Luisa Carvalheiro, PhD >> Southern African Biodiversity Institute, Kirstenbosch Research Center, >> Claremont >> & University of Pretoria >> Postal address - SAWC Pbag X3015 Hoedspruit 1380, South Africa >> telephone - +27 (0) 790250944 >> carvalhe...@sanbi.org >> lgcarvalhe...@gmail.com >> >> ______________________________________________ >> 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. >> > -- Luisa Carvalheiro, PhD Southern African Biodiversity Institute, Kirstenbosch Research Center, Claremont & University of Pretoria Postal address - SAWC Pbag X3015 Hoedspruit 1380, South Africa telephone - +27 (0) 790250944 carvalhe...@sanbi.org lgcarvalhe...@gmail.com ______________________________________________ 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.
