[R] lme4 question

[Lawrence Hanser]

Re Doug's comment:

I apologize for being incomplete--I do know better.

I did explicitly include a data statement in the models, but didn't
write the model statements properly in my post.  Here are the actual
model statements:


mod1 <- lmer(y ~ category + subcomp + (1 | id), data=prepchiefs08rm)
mod2 <- lmer(y ~ category + subcomp + category*subcomp + (1 | id),
data=prepchiefs08rm)

Thanks.

On Wed, Oct 22, 2008 at 2:41 PM, Douglas Bates <bates at stat.wisc.edu> wrote:
> On Wed, Oct 22, 2008 at 4:18 PM, Lawrence Hanser <larry at hanser.net> wrote:
>> Dear R Colleagues,
>>
>> I run the following two models:
>>
>> mod1 <- lmer(y ~ category + subcomp + (1 | id))
>> mod2 <- lmer(y ~ category + subcomp + category*subcomp + (1 | id)
>>
>> where:
>> category has 4 possible values
>> subcomp has 24 possible values
>> id has approx 120 values (id is nested within category, and in unequal
>> numbers--i.e., unbalanced)
>>
>> Then to look for differences in the models I run:
>>
>> anova(mod1, mod2)
>>
>> I receive this warning message after the last command:
>
>> In data != data[[1]] :
>>  longer object length is not a multiple of shorter object length
>
> That piece of code is comparing the values of the data arguments in
> the call slot of the fitted models.  These are what are known as
> matched calls (produced by the function match.call).  The second model
> you show seems incomplete.  Did you miss a closing parenthesis or did
> you have an explicit data argument?
>
> I always use an explicit data argument and I probably implicitly
> thought that others would do that when I wrote the piece of code in
> question.  I suppose I could remove that check or replace it with a
> better one.  The purpose of the code is to determine if it is
> reasonable to compare the model fits by checking if the models were
> fit to the same data.
>
>
>> I think I know why this is happening (i.e., the two models are of
>> different length).  Is my surmise correct?  If I am correct I don't
>> think I should worry.  Should I?
>>
>> Thanks.
>>
>> ______________________________________________
>> 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.
>>
>
> ______________________________________________
> 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.
>