[R-meta] Interpreting variance components in rma.mv
James Pustejovsky
jepu@to @end|ng |rom gm@||@com
Sun Aug 21 21:07:51 CEST 2022
Hi Yuhang,
But is it appropriate to assume that true effects' dispersion at time 0 and
> time 1 is exactly the same (equality of variances across time points)?
>
The model you've fit assumes that the variances are equal across time
points. Whether this assumption is appropriate is an empirical question and
something you'll need to gauge for yourself. You could probe it by, for
example, fitting a model that allows the variance components to differ by
time point:
rma.mv(yi ~ 0 + cat_mod * time + covariates, random = ~ time |
study/effect, struct = "UN")
And then comparing the fit of this model to the fit of the model that
assumes compound symmetry (i.e., your initial model).
James
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