[R-meta] Meta-analysis per level or meta-regression

[Catia Oliveira]

Dear all,

Does anyone know of a manuscript that has compared the effect sizes when
running separate meta-analyses per level of a variable of interest against
those of running a meta-regression where we remove the intercept?

e.g.,

### mixed-effects meta-regression model with categorical moderator
res <- rma(yi, vi, mods = ~ alloc, data=dat)
res

You will find:

Test of Moderators (coefficients 2:3):
QM(df = 2) = 1.7675, p-val = 0.4132

Model Results:

                 estimate      se     zval    pval    ci.lb   ci.ub
intrcpt           -0.5180  0.4412  -1.1740  0.2404  -1.3827  0.3468
allocrandom       -0.4478  0.5158  -0.8682  0.3853  -1.4588  0.5632
allocsystematic    0.0890  0.5600   0.1590  0.8737  -1.0086  1.1867


Instead of doing this, we could also run one meta-analysis for allocrandom
and another for allocsystematic.
I know the results will be similar, I just need to have something that
proves this beyond running the model and presenting the findings. Also,
meta-regression allows us to compare the different levels, which is the
point. I don't understand why we are questioned about this when running a
meta-regression but if this was a linear regression using this approach
would be standard.

Best wishes,

Catia

-- 
Cátia Margarida Ferreira de Oliveira
Research Associate
Department of Psychology, Room C222
University of York, YO10 5DD
Twitter: @CatiaMOliveira
pronouns: she, her

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