I'm doing an extracurricular programme at my university as part of which we have to write a review article. My supervisor agreed to a meta-analysis. I want to investigate whether the preprocessing of the data (log-transformation of RTs & Outlier trimming/ only outlier trimming/ only log-transformation / raw data) influences the outcome across multiple studies.
For that, I want to analyse all studies on that topic, that my supervisor´s lab ran (ca 10 unpublished + two published papers from other labs) with each of the possible preprocessing pathways. I then planned to conduct a meta-analysis of each pathway separately and compare the mean effect sizes of each preprocessing pathway. How do I account for the fact that each of the 4 meta analyses uses the same studies? Because I think I remember that meta-analysis assumes independence.
Some advice and/or literature would be appreciated. Particularly, if anyone knows a (free) programme that allows me to correct for dependency, that´d be great. And how do I best compare the mean effect sizes of the different meta-analyses? I found a post on here suggesting simply subtracting ES 1 from ES 2. Or should I run a meta-analysis again?
I'm willing to use any free non-programming based program, i.e, preferably not R.