= Formula for the standard error of a Cohen's d =

According to p238 of standard text on meta-analysis in social science The Handbook of Research Synthesis, the variance of Cohen's d  is 

( [(n1 + n2)/(n1*n2)]  + d^2 ^ / 2*(n1 + n2 − 2) )*([n1 + n2] / [n1 + n2 − 2] ), 

where n1 and n2 are the sample sizes of the two groups being compared and d is Cohen's d .

Taking the square-root of this variance gives the standard error of d , needed as input by several of the user-written meta-analysis packages for Stata. (Some of them also accept confidence intervals as input, but they simply convert them to standard errors internally anyway.)

See also [[attachment:sed.pdf | equation 4.20 here]] and [[
https://stats.stackexchange.com/questions/77269/statistical-comparison-of-2-independent-cohens-ds | here which also gives standard error formulae for d]].