[R] Metafor - rma.mv function - variance components

[Lists at dewey.myzen.co.uk]

Carlijn Wibbelink <wibbeltjec at hotmail.com> wrote :

Dear Carlijn
I think that if you set sigma2 to a vector of length 2 it will be possible.

> Hi all,
> 
> I have a question about metafor and the rma.mv function. I have fitted a
> multivariate model (effect sizes are nested within studies) and I've found two
> variances: 
> 
> Variance Components: 
>                       estim    sqrt     nlvls  fixed  factor
> sigma^2.1  0.0257  0.1602     72     no       y
> sigma^2.2  0.0694  0.2635     10     no      ID 
> 
> I want to test whether there is significant variantion between the effect sizes
> within studies (sigma^2.1: 0.0257) and/or between studies (sigma^2.2: 0.0694).
> In metaSEM you can fix for example the variance within studies (sigma^2.1) to
> zero to test whether there is a significant difference in fit between the models
> (and if so, then there is significant heterogeneity between the effect sizes
> within studies). I was wondering if this is also possible in metafor. If I fix
> sigma2 to zero, then both variances are fixed to zero. However, I want to fix
> only one variance to zero. 
> I hope that someone can help me. Thank you in advance!
>  		 	   		  
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org
> mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.