Metafor: difference between SMCC and SMDH, formula SMDH, alternative to SMCC

Hi everyone,

I'm new to R and using the metafor package for a meta-analysis. The studies I collected show the difference in means between two conditions, means and standard deviations are given in the studies, however, I had to estimate correlations between conditions because they were not given. I was told I could use SMCC as a measure in the escalc function. Now I'm wondering:

  1. What's the difference between SMCC and SMDH? The descriptions sound very similar.

  2. I read that SMCC is calculated as (m1i-m2i)/sqrt(sd1i^2 + sd2i^2 - 2*ri sd1i sd2i) but could not find out how SMDH is calculated, does anyone know? (Also, I tried calculating the SMCC by hand using this formula, but got a different result than the one R provided)

  3. Since r values are not given in the articles and the SMCC requires r, I'd prefer a measure that does not involve r but maybe uses F-, t- or d-values in some way. Does anyone know what I could use?

Thanks a lot in advance!

Cheers, Tanja

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