test the sig. of random slope, if you compare these two
(1 | Subj): random intercept
(Task | Subj): random intercept and random slope
but can you do (Task | Subj)? I thought some levels of Subj is present in
given levels of Task, so is nested.
2010/12/10 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
> >>>>
> >>>> 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@r-project.org mailing list
> >>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> >>>
> >>>
> >>
> >> _______________________________________________
> >> R-sig-mixed-models@r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> >>
> >
>
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