Re: [R] How to assess significance of random effect in lme4

From: Shige Song <shigesong_at_gmail.com>
Date: Wed 17 Aug 2005 - 21:49:53 EST

Hi Harold,

Thanks for the reply. I looked at my outputs using str() as you suggested, here is the part you mentioned:

  ..@ bVar     :List of 2
  .. ..$ commu  : num [1, 1, 1:29] 5e-10 5e-10 5e-10 5e-10 5e-10 ...
  .. ..$ bcohort: num [1, 1, 1:6] 1.05e-05 7.45e-06 6.53e-06 8.25e-06
7.11e-06 ...

where commu and bcohort are the two second-level units. Are these standard errors? Why the second vector contains a series of different numbers?

Thanks!

Shige

On 8/17/05, Doran, Harold <HDoran@air.org> wrote:
>
>
> You can extract the posterior variance of the random effect from the bVar
> slot of the fitted lmer model. It is not a hidden option, but a part of the
> fitted model. It just doesn't show up when you use summary().
>
> Look at the structure of your object to see what is available using str().
>
> However, your comment below seems to imply that it is incorrect for lmer to
> report SDs instead of the standard error, which is not true. That is a
> quantity of direct interest.
>
> Other multilevel programs report the same exact statistics (for the most
> part). For instance, HLM reports the variances as well. If you want the
> posterior variance of an HLM model you need to extract it.
>
>
>
> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch on behalf of
> Shige Song
> Sent: Wed 8/17/2005 6:30 AM
> To: r-help@stat.math.ethz.ch
> Cc:
> Subject: [R] How to assess significance of random effect in lme4
>
> Dear All,
>
> With kind help from several friends on the list, I am getting close.
> Now here are something interesting I just realized: for random
> effects, lmer reports standard deviation instead of standard error! Is
> there a hidden option that tells lmer to report standard error of
> random effects, like most other multilevel or mixed modeling software,

> so that we can say something like "randome effect for xxx is
> significant, while randome effect for xxx is not significant"? Thanks!
>
> Best,
> Shige
>
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>



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Aug 17 22:03:51 2005

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