Hi All,
Page 13 of *THIS ARTICLE
<https://cran.r-project.org/web/packages/robumeta/vignettes/robumetaVignette.pdf>*
(*top of the page*) recommends that if a *continuous moderator *varies
both within and across studies in a meta-analysis, a strategy is to break
that moderator down into two moderators by:
*(a)* taking the mean of each study (between-cluster effect),
*(b)* centering the predictor within each study (within-cluster effect).
BUT what if my original moderator that varies both within and across
studies is a *"categorical" *moderator?
I appreciate an R demonstration of the strategy recommended.
Thanks,
Simon