[R-sig-ME] lme4 error: "Number of levels of a grouping factor . . ."

[Brent Pedersen]

On Wed, Jul 27, 2011 at 7:34 AM, Ben Bolker <bbolker at gmail.com> wrote:
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> On 07/27/2011 03:29 AM, Martin Maechler wrote:
>>>>>>> Gabrielle Miller-Messner <gmessner at ucdavis.edu>
>>>>>>>     on Tue, 26 Jul 2011 22:26:38 -0700 writes:
>>
>>     > Hello, I have count/proportion data and I am trying to
>>     > account for overdispersion in a logistic regression. With
>>     > the following code from lme4 I receive the following error
>>     > message:
>>
>>     >> glmm = glmer(cbind(fertilized, unfert) ~ density.class +
>>     >                (1|individual), family = binomial)
>>     > Number of levels of a grouping factor for the random effects
>>     > is *equal* to n, the number of > observations
>>
>>     > This problem was mentioned in Warton and Hui 2011, so I
>>     > imagine it may have been fixed recently.  I downloaded the
>>     > most recent version of lme4 available through the command
>>     > install.packages("lme4").  Is there an updated version of
>>     > the package available in a different form?
>>
>> {yes, lme4a on R-forge, but that's not the issue now, and not
>>  something I'd recommend to get into just right now ...}
>>
>> Well, I'm puzzled that you say you get an *error* with the above
>> message.
>> You should get a message, but no error in the case of glmer().
>
>  Probably this is indeed just a warning message and not an error?
>   Gabrielle, does the function return an answer (i.e. a fitted model)?
>

Hi, I've hit this as well. with:

> packageVersion("lme4a")
[1] ‘0.999375.67’

(should I be using another version?)
and code:

"""
library(lme4a)

d = data.frame(a=runif(200),
               b=sample(c(strsplit("ABCDEF", "")[[1]]), 200, replace=T),
               c=as.factor(1:200))
# d$c[2] = d$c[1]

fm = glmer(a ~ b + (1|c), d)
"""
it shows:
"""
Error in lmer(formula = a ~ b + (1 | c), data = d) :
  number of levels of each grouping factor must be less than number of obs
"""

and if i uncomment that line to make the number of grouping factors (c) less
than the number of obs, it runs successfully.
not sure if this is different for binomial...


>>
>>
>> Just to be sure:  What does
>>      packageVersion("lme4")
>> say for you?
>>
>> Martin
>>
>>
>>     > I am using R version 2.13.1 on OS 10.6.4.
>>
>>     > thank you!  Gabrielle
>>
>>     > --
>>     > Gabrielle Miller-Messner Graduate Student Center for
>>     > Population Biology Section of Evolution and Ecology
>>     > University of California, Davis 1 Shields Avenue Davis,
>>     > California 95616 gmessner at ucdavis.edu
>>
>>     >         [[alternative HTML version deleted]]
>>
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