[R-sig-ME] Continuous vs. categorical correlated group effects

[Drager, Andrea Pilar]

summary(flor_data)

  species_id         binary_individual_response

  Length:29609       Min.   :0.00000
  Class :character   1st Qu.:0.00000
  Mode  :character   Median :0.00000
                     Mean   :0.06018
                     3rd Qu.:0.00000
                     Max.   :1.00000

   species_abund
   Min.   :  11.23
   1st Qu.:1996.23
   Median :2548.23
   Mean   :3438.20
   3rd Qu.:5310.23
   Max.   :6116.23


The following is also the case:

Won't run-->glmer(binary_indivdual_response ~ species_abund  
+(1|species_id),family=binomial(link='logit')

Runs-->glm(binary_individual_response ~ species_abund + species_id,  
family=binomial(link='logit')


Quoting Ben Bolker <bbolker at gmail.com>:

> Can you show us the summary() of your data?
>   Is it possible you have complete separation in your continuous predictor?
>
> On 18-01-02 02:38 PM, Drager, Andrea Pilar wrote:
>>
>> Hi All,
>>
>> I am having trouble running a Bayesian mixed model in MCMCglmm where I
>> have individual-level data for my response variable, and species-level
>> data as the random effect (such as "species"), plus any other
>> species-level continuous variable, such as abundance, in the model. But
>> if the the other species-level variable is categorical--whether because
>> I make it a random effect or because it is in fact categorical--the
>> model runs! Could someone please explain the stats behind this?
>>
>>
>> prior = list(R = list(V = 1, nu = 0, fix = 1),  G = list(G1=list(V =
>> 1,nu = 0.002)))
>>
>> Won't run-->MCMCglmm(binary_individual_repsonse ~ species_abund_continuous,
>>                      random = ~ species_id_categorical, family =
>> "categorical")
>>
>>             Error : Mixed model equations singular: use a (stronger) prior
>>
>>
>> Runs-->MCMCglmm(binary_individual_response ~ 1,
>>                 random = ~ species_abund_categorical +
>> species_id_categorical, family = "categorical")
>>
>> Runs-->MCMCglmm(binary_individual_response  ~ species_id_categorical,
>>                 random = ~ species_abund_categorical, family=
>> "categorical")
>>
>>
>> Thanks in advance!
>> Andrea Pilar Drager
>> PhD. student
>> Ecology and Evolutionary Biology, Rice University
>>
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>
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Andrea Pilar Drager
PhD. student
Ecology and Evolutionary Biology, Rice University