[R] lmer - error asMethod(object) : matrix is not symmetric

[Luisa Carvalheiro]

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 <bates at 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
> <lgcarvalheiro at 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
>> Carvalheiro at sanbi.org
>> lgcarvalheiro at gmail.com
>>
>> ______________________________________________
>> R-help at 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
Carvalheiro at sanbi.org
lgcarvalheiro at gmail.com