[R-meta] Studies that use several formulas to capture the same outcome

Hello All,

Studies in my study pool have used different formulas to capture the same
construct. Ideally, I want to be able to generalize beyond the set of
formulas used in my study pool.

But, given the structure of my data (below), I wonder whether to use
"formula" as a random effect nested (while it doesn't vary within studies)
in studies or simply use "formula" as a study-level moderator?
```
rma.mv(yi, vi, random = ~ 1 | study/formula)
# OR
rma.mv(yi ~ formula, vi, random = ~ 1 | study)
```
Many thanks, Jack

study  formula
1      2
1      2
2      1
2      1
3      1
4      2
4      2