[R-lang] Re: p-values for mixed effects models with random slopes

[Sverre Stausland]

Hi Alex,

pvals.fnc in languageR just uses the mcmcsamp function in lme4. I've
also experienced pvals.fnc failing, but as far as I know, that's
because Doug Bates chose to not let mcmcsamp work, because he didn't
trust its results.

That said, pvals.fnc worked just fine when I used it about a week ago.
I assume this means mcmcsamp has been implemented in the newest
version of lme4. Try using the latest version of lme4.

If that doesn't work, the standard approach to get p-values from
linear mixed models is to do likelihood ratio tests. If you test fixed
effects, though, remember to fit the models with maximum likelihood
fitting, and _not_ with restricted maximum likelihood (i.e. include
REML=FALSE in the call). (There's an explanation for why in Pinheiro &
Bates' 2000 book).

-Sverre

On Mon, Jan 17, 2011 at 9:53 PM, Alex Fine <afine@bcs.rochester.edu> wrote:
> Hi,
>
> I would imagine many or most of you are aware of the fact that the pvals.fnc
> function in the languageR package cannot currently estimate p-values for
> models that include random slopes.  Because we all need p-values, I'm
> guessing someone out there has developed a way of getting them from such
> models.  Has anyone implemented something that does this, or have any
> thoughts on this issue?
>
> Thanks!
> Alex
>
>