[R-sig-ME] F and P values for random factors

[Philippi, Tom]

A perhaps more comprehensive answer is available in the draft
r-sig-mixed-models FAQ:
http://glmm.wikidot.com/faq

Tom 2


On Fri, Feb 5, 2016 at 4:05 PM, Alex Fine <abfine at gmail.com> wrote:

> Hi Mahendra,
>
> You can assess the significance of both fixed and random factors using
> likelihood ratio tests.  Say you want to test the significance of predictor
> A in a model with predictors A and B and random slopes for A.  You can do:
>
> full_model = lmer(y ~ A + B)
> model_without_A = lmer(y ~ B)
> anova(full_model, model_without_A)
>
> The anova() function in this case will return a chi-squared score (df =
> number of predic) and a p-value.  The same procedure can be used for random
> effects, e.g.:
>
> full_model_2 = lmer(y ~ A + B + (1+A | random_thing)
> model_without_random_slope_for_A = lmer(y ~ A + B + (1 | random_thing)
> anova(full_model, model_without_random_slope_for_A)
>
> This works because the log-likelihoods of nested models, in the limit,
> approximate a chi-squared distribution.
>
> See:  https://en.wikipedia.org/wiki/Likelihood-ratio_test
>
> Or maybe that wasn't what you were asking at all.
>
> Also I think you forgot to attach the file.
>
> Hope that helps!
> Alex
>
>
> On Thu, Feb 4, 2016 at 8:32 PM, Mahendra Dia <diamahendra at gmail.com>
> wrote:
>
> > Hi.
> >
> > I am reaching you out to learn how to compute F ratio and P values for my
> > experiment where all the factors are treated as random factors.
> > Please see the attached file where I explained my treatments and sample
> > data.
> >
> > I thank you in advance.
> >
> > Sincerely,
> > Mahendra-
> > _______________________________________________
> > R-sig-mixed-models at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> >
>
>
>
> --
> Alex Fine
> Ph. (336) 302-3251
> web:  abfine.github.io/
>
>         [[alternative HTML version deleted]]
>
> _______________________________________________
> R-sig-mixed-models at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>

	[[alternative HTML version deleted]]