[R-meta] metafor::rma-function: Statistically significant interaction, but increased tau2 – and how to get the slope from the output

Wolfgang Viechtbauer wo||g@ng@v|echtb@uer @end|ng |rom m@@@tr|chtun|ver@|ty@n|
Sat Aug 3 17:45:50 CEST 2019


Thanks for the feedback. Ok, then the last model is overparameterized, but 
this model:

rma.mv(logOR, logOR.var, mods = ~ CF1_Women..IMP,
        random = ~ CF1_Women..IMP | id, struct="GEN", data=d)

(i.e., random intercepts and slopes for the different meta-analyses) 
should be fine. But I understand your preference for sticking to the 
protocol and using fixed effects for meta-analyses and the interactions is 
also fine.

Best,
Wolfgang

On Fri, 2 Aug 2019, Sabrina Mai Nielsen wrote:

> Thanks a lot for very fast response!
>
> 1) Ok, I am happy to hear that it is a known issue and not necessarily 
> caused by errors in my coding.
>
> 2) Perfect, that makes sense. Thanks a lot for making that clear for me.
>
> 3) Thanks a lot for the suggestions - I will try those models out! For 
> my study, however, I have already protocolized the model I am using, so 
> I may have to stick with that. - For the model that allows tau^2 to be 
> different for every level of id, I do get the same as with the 'subset' 
> model, as you said - cool! - The multilevel model adding random effects 
> for meta-analyses was definitely among our considerations, however, we 
> found it rather complex (e.g. by resulting in two variance components, 
> sigma^2.1 and sigma^2.2) and we ended up choosing fixed effects for 
> meta-analyses. - The profile plots are peaking nicely for the two first 
> plots (σ^2 and tau1^2), but not for the last two plots.
>
> Thanks again
>
> Best,
> Sabrina


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