I'm running a multi-level moderator meta-analysis using the R package
metafor. To derive $I^2$ for the metafor analysis as a whole, which doesn't come out automatically for multi-level models, I've used the formulas described here.
However, I've seen meta-analysis articles where heterogeneity measures, such as $I^2$, are reported for the individual levels in the moderator analysis.
How would these be computed? I realize that I could run subset analyses for each level, but could I somehow get the values directly from the moderator analysis? Does it even make sense to ask for heterogeneity measures for each of the levels in a moderator analysis?