[R-meta] Questions about Omnibus tests

Michael Dewey li@t@ @ending from dewey@myzen@co@uk
Thu Oct 25 17:33:21 CEST 2018

Dear Rafael

I think the issue is that the test of the intercept tests whether that 
might be zero whereas the test of the moderator tests whether the other 
two coefficients are zero. If you remove the intercept from the model 
you should get a test for the moderator with 3 df (not 2 as at pesent) 
which tests whether all three coefficients are zero which seems to be 
what you are after.


On 25/10/2018 16:00, Rafael Rios wrote:
> Dear Wolfgang and All,
> I am conducting a meta-analysis to evaluate the effects of mate choice 
> on the outcome. My dataset and script follow on attach. I found 
> conflicting results with the omnibus test. The QM-test had a 
> non-significant p-value, while z-test shows a significant p-value for 
> the intercerpt (corresponding to the treatment of female choice). When I 
> undertook pairwise comparisons, I also found differences among 
> treatments consistent with the z-test results. You can also observe 
> these differences in the graph. What exactly is each test (QM and z) 
> evaluating? Why is QM-test reporting a p-value higher than 0.05, even 
> when there is differences in pairwise comparisons? I also found a 
> negative value for I². Is there any problem with the model to report 
> such result? My questions are organized inside the script. Any help will 
> be welcome.
> Best wishes,
> Rafael.
> __________________________________________________________
> Dr. Rafael Rios Moura
> /scientia amabilis/
> Behavioral Ecologist, PhD
> Postdoctoral Researcher
> Universidade Estadual de Campinas (UNICAMP)
> Campinas, São Paulo, Brazil
> Currículo Lattes: http://lattes.cnpq.br/4264357546465157
> ORCID: http://orcid.org/0000-0002-7911-4734
> Research Gate: https://www.researchgate.net/profile/Rafael_Rios_Moura2
> <http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4244908A8>
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