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[R-meta] OR using metafor: Standard group with many zeros

Wolfgang Viechtbauer 
Dear Nelson,

1) You mean that there are studies where there were 0 patients (not just 0 events, but actually no participants) in one of the two groups? If so, I don't see how such studies could be included in a meta-analysis that aims to estimate ORs. Those are essentially one-arm studies, so they don't provide any information about group differences.

2) help(rma.glmm) explains what nAGQ represents. When using glmer() for fitting the 'UM.RS' model, one has to use the Laplacian approximation (i.e., nAGQ=1). You could try using:

control=list(package="GLMMadaptive")

which then uses the GLMMadaptive package, which does allow for using proper quadrature when fitting the model.

As for the convergence warning - that comes from glmer(). It is quite quick to flag potential non-convergence, but this may be a false positive. Again, you could compare results when using GLMMadaptive.

Best,
Wolfgang

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Nelson Ndegwa OR using metafor: Standard group with many zeros Apr 18 Wolfgang Viechtbauer OR using metafor: Standard group with many zeros Apr 18 Nelson Ndegwa OR using metafor: Standard group with many zeros Apr 22