I am calculating Hedge's g for effect sizes, so I am pulling means, SDs, and Ns, from each study. However, one study did a Mann-Whitney U test, and so reports Mean Rank, Sum of Ranks, U, Z, and r (as an effect size).
Is there any way to convert this into a hedge's g and get its weighting, so that I can include it in the meta-analysis?
Many thanks.
Go to https://www.psychometrica.de/effect_size.html for effect size online calculators. #11 should do what you want. To convert from Cohen's d to Hedges' g, multiply by J. See the attached file for calculating J; n1 and n2 are sample sizes. These formulas are from "Introduction to Meta-Analysis" by Borenstein et al (2009).
You could use the CMA software as it can help you convert from one type of effect size to another without altering the input data
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