"Mean pooled difference" or "pooled mean difference"? Perhaps this is purely semantics but meta-analyses use these in interchangeably but which is more legitimate or are neither because there should be a hyphen?
I would say pooled mean difference because you're pooling the mean difference. I wouldn't use a hyphen because the "mean difference" is being pooled, not just the "mean".
No this question doesn't belong in English literature or semantics because it's a statistical term and sense of it must be made from a statistical standpoint

Mean difference is just a type of effect size. We also have median difference, Cohen's d and Hedges' g which are standardized mean difference, etc. In meta-analysis, these effect sizes are pooled, weighted, or averaged then you get things like pooled mean difference.
