[Q] What effects to include in meta-analysis for papers with multiple estimates of same outcome?
I am a PhD student conducting a meta-analysis. I have already extracted the data from each paper and calculated standardized mean differences (SMDs) for all my outcomes. The next step is the actual meta-analysis, which will be a robust, random effects meta-analysis (robumeta in Stata) to account for differences in study settings and multiple outcomes per paper. Here lies my question. I am unsure which effect sizes to include in the analysis. Most papers measure the outcome variable as an overall index as well as separated into sub-indices. Some papers use a different estimation method as robustness checks or carry out sub-group/heterogeneity analysis. Others create the index in two different ways and calculate effects for both. Lastly, some papers estimate the effect on the main outcome for multiple follow-up periods separately as well as pooled over all periods.
Would I include all potential estimates of a paper in the meta-analysis? For example, the overall index and the sub-indices, the outcomes for the overall sample as well as for sub-samples and so on. (My analysis includes 28 papers if that is relevant.)
Thank you very much for your help! If you can refer me to further reading about this, I would also be very happy!