The sampling variances are the 'residual variances'. And since the sampling variances are heteroscedastic, there is not just one residual variance, but each study/estimate has its own sampling variance. A common approach in meta-analysis is to compute some kind of 'average/typical' sampling variance and then use that in computing various statistics (like the I^2, which is sort of an ICC). See, for example:
http://www.metafor-project.org/doku.php/faq#how_are_i_2_and_h_2_computed_ihttp://www.metafor-project.org/doku.php/tips:i2_multilevel_multivariate
Best,
Wolfgang
-----Original Message-----
From: Rafael Rios [mailto:biorafaelrm at gmail.com]
Sent: Friday, 29 September, 2017 21:59
To: r-sig-meta-analysis at r-project.org; Viechtbauer Wolfgang (SP); Nelson Silva Pinto
Subject: Intraclass correlation
Dear metanalysts,
I'm conducting a meta-analysis involving almost 300 species. However, I had problems in insert a phylogenetic correlation matrix in the function rma.mv. Dr. Wolfgang is helping me, but I was wondering if I can calculate intraclass correlation (ICC) to evaluate the necessity to conduct a phylogenetic metanalysis. The ICC is calculated using the species variance divided by the same value plus the residual variance. When I conduct mixed models using function rma.mv, I can vizualize the variance of the random variables. However, I did not find the residual variance. Do you may clarify how may I calculate ICC using metafor package? And how may I obtain values of residual variance? Any help is welcome.
Best wishes,
Rafael R. Moura.
scientia amabilis
Doutorando da P?s-gradua??o em Ecologia e Conserva??o de Recursos Naturais
Universidade Federal de Uberl?ndia, Uberl?ndia, MG, Brasil
ORCID:?http://orcid.org/0000-0002-7911-4734
Curr?culo Lattes:?http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4244908A8
Research Gate:?https://www.researchgate.net/profile/Rafael_Rios_Moura2