I am currently running a meta-analysis exploring effects of mindfulness interventions on creativity. I am using JASP software to run my meta-regression, which needs effect size and standard error.

I understand standard error is standard deviation divided by the square root of the sample size, but which standard deviation do I use in this equation? I am looking at some data collected pre and post intervention and also data comparing control groups to intervention groups. So, would I use the post-intervention SD when computing standard error for pre/post RCT's? And the experimental group SD when computing standard error for control/experimental RCT's?

Any help on this would be great - thank you!