[R-sig-ME] Comparing models with different random effects

[Douglas Bates]

On Fri, Dec 10, 2010 at 9:27 AM, Gang Chen <gangchen6 at gmail.com> wrote:
> Thanks for the quick help, Dr. Bates!
>
>>> My second question is still open: I tend to believe that (1 | Subj) is
>>> nested within (Task | Subj) since the first model has one parameter
>>> (variance) which can be viewed as multiple variances in the second
>>> model being constrained as equal, but I would still appreciate it if
>>> somebody could confirm this.
>>
>> If you are using "is nested within" to mean "is a submodel of" then
>> the answer is yes.
>
> The reason I'm asking about the relationship between the two models is
> whether I could use anova() to compare the two models. So, under this
> context is likelihood ratio test meaningful?

If that is the only difference between the models, yes.

>>>> 2010/12/9 Gang Chen <gangchen6 at gmail.com>
>>>>>
>>>>> Suppose that there are multiple task types (Task) and each task type
>>>>> is represented with a few questions (Item). And all subjects (Subj)
>>>>> answer the same questions (Item).
>>>>>
>>>>> How do I compare a model with (1 | Subj) + (1 | Item) versus one with
>>>>> (1 | Subj) + (1 | Subj:Item) in lmer()? Through AIC/BIC (assuming the
>>>>> fixed effect remain the same)? Would it make more sense to consider (1
>>>>> | Subj) + (1 | Subj:Item) + (1 | Item)?
>>>>>
>>>>> Is (1 | Subj) considered as nested within (Task | Subj)?
>>>>>
>>>>> Thanks,
>>>>> Gang
>>>>>
>>>>> _______________________________________________
>>>>> R-sig-mixed-models at r-project.org mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>>>>
>>>>
>>>
>>> _______________________________________________
>>> R-sig-mixed-models at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>>>
>>
>