Skip to content
Prev 3715 / 5636 Next

[R-meta] (Too) Many effect sizes for one single group

Dear Catia,

under certain circumstances it could be a valid concern.
Fortunately, one can test it directly. One could conduct a sensitivity 
analysis to examine the impact in your specific case: Do the results 
(mean effect, standard error etc.) change much if you exclude certain 
effect sizes?

Example:
Scenario 1: All effects are considered
Scenario 2: The study with "too many" effect sizes is excluded
Scenario 3: Only one or several effect sizes from the problematic study 
are considered, e.g. by using the sample() function and choosing a 
certain number of effects randomly. One could also repeat this procedure 
to check the influence of the selection procedure.

If the estimates differ only slightly across the analyses then you could 
proceed with the original idea (including all effects). You could 
mention in the report that this decision is based on some sensitivity 
analyses that you've conducted.


Best wishes
Lukasz