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

[Gang Chen]

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?

Thanks,
Gang


>>> 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
>>>>
>>>> _______________________________________________
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>>>
>>>
>>
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>