How to assess significance of random effect in lme4
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 at 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 at stat.math.ethz.ch on behalf of Shige Song Sent: Wed 8/17/2005 6:30 AM To: r-help at 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
______________________________________________ R-help at 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