[R-meta] I2 and R2 estimation

[Lukasz Stasielowicz]

Hi,

For I2, there is a vignette on the official metafor page: 
https://www.metafor-project.org/doku.php/tips:i2_multilevel_multivariate


For R2, you need the model with the moderator (res1) and the model 
without moderators (e.g., res).

If you want to estimate R2 separately for different levels, then you can 
use the tau2 values (sigma2) from the respective levels, e.g.,
(res$sigma2[1] - res1$sigma2[1]) / res$sigma2[1]
(res$sigma2[2] - res1$sigma2[2]) / res$sigma2[2]
If you prefer to estimate only one R2 value, then the following code 
will suffice:
(sum(res$sigma2) - sum(res1$sigma2)) / sum(res$sigma2)



Best wishes,
-- 
Lukasz Stasielowicz
Osnabrück University
Institute for Psychology
Research methods, psychological assessment, and evaluation
Lise-Meitner-Straße 3
49076 Osnabrück (Germany)
Twitter: https://twitter.com/l_stasielowicz

On 17.07.2023 12:00, r-sig-meta-analysis-request using r-project.org wrote:
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> Dear All,
> 
> Hi, everyone! I am currently taking the multilevel meta-analysis where effect sizes can be nested in studies. I am wondering how to get  the I2 index for hetegeneity test as well as R square of the moderator analysis under rma.mv function.  What are the codes to calculate those values?
> 
> res1 <- rma.mv(yi = yi,
>                 V = vi,
>                 test="t",
>                 mod=~ mod1
>                 random = list(~ 1 | Study_ID, ~ 1 | Study_ID/correlation_ID),
>                 data = es)
> res1
> 
> the fitstats function did not give  R square.
> 
> Thank you for your attention.
> 
> Best Wishes
> 
> Shuyi (Qiao)
> 
> 
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