[R-meta] Questions metafor random slope

[Mathias Weis Damkjær]

Hello everyone,


I have a few questions about a more complicated model specification in metafor.
I have also created a stackoverflow thread with no replies yet here: https://stackoverflow.com/questions/79165730/random-slopes-and-intercepts-in-the-metafor-package-model-specification-and-out



I have read the e-mail correspondence: https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2019-August/001650.html with interest.



However, I do have some questions.



  1.  Question 1:


The model specification:

  *   res <- rma.mv(logOR, logOR.var, mods = ~ CF1_Women..IMP, random = list(~ CF1_Women..IMP | id, ~ 1 | row), struct="GEN", data=d)

Adds a multilevel structure AND random slopes for the covariate within meta-analyses.



I was wondering why one should not specify the model with: ~ 1 | id/row as the last element in the list of random-effects? That is the notation for instance in the lme4 package.



  1.  Question 2:



The tau2 estimates (variance components) from this model:
Variance Components:



            estim    sqrt  nlvls  fixed    factor

sigma^2    X  X    X     no  trial_id



outer factor: id       (nlvls = X)

inner term:   ~factor (nlvls = X)



              estim    sqrt  fixed  rho:  intr    c_SP

intrcpt        X      X                 no           -  X

factor     X        X no          no       -

Sigma2 is for trial_level.

Is it correct that �intrcpt� is for the meta-analyses level?


Thanks in advance!

Best,
Mathias, Phd. Student

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