Effect Size - Cohen's D calculation

#1
I had a question about how to calculate Cohen's D a particular situation for my meta-analysis. I am a first year grad student, so my familiarity with statistics is somewhat limited!

The study design - participants are assigned to one of two groups (parallel design), but not a true RCT because both are interventional (no control group).

What I want to calculate - I want to include both interventions in my meta-analysis, and calculate an effect size for each of them (cohen's D). I am thinking I will compare the pre and post intervention scores for each group, for my effect sizes.

Information I have - I have pre and post means and standard deviations for each of the groups for my outcome measure. I also have the sample size of each group, of course. The paper, also reports the effect sizes (using ηp^2) for a 2 X 2 ANOVA (intervention groups - intervention1, intervention 2 - BY time - baseline, post)...for the "time factor" of one of the outcomes I want to look at. So have the the F-statistics value and the p-value for that....not sure if this is relevant. However, I want the effect of each individual intervention using cohen's D.
(If wanted to reference, the paper is pubmed ID# 28944527, and is also attached..I'm interested in analyzing some of the psychological questionnaire data...outcomes for body image measures)

Do you know which formula I would use? I'm confused because I'm not sure if I need to you the pooled SD or the individual SD of each group in this situation.

Thank you in advance!
 

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