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I am doing a meta-analysis and one of the papers report d instead of SD. I do also have sample size and mean for each group, but I don't have the SD for each group.

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A bit of simple algebra should suffice here.

Let $X_1$ and $X_2$ be the means which you say you have, $d$ be Cohen's $c$ and $s$ be the pooled standard deviation.

$$ d = \frac{X_1 - X_2}{s} $$

Multiply both sides by $s$

$$ s * d = X_1 - X_2 $$

Now divide both sides by $d$

$$ s = \frac{X_1 - X_2}{d} $$

which is the desired result.

Note that this is more complex if what they are reporting is not in fact Cohen's $d$ but the bias corrected version usually known as Hedges' $g$.

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