Formula for Cohen's d 95% CI using estimated marginal means

Discuss the jamovi platform, possible improvements, etc.

by Francisco » Sat Dec 12, 2020 6:38 am

Hello,

I was conducting an ANCOVA using a fixed factor with two groups, a continuous dependent variable, and a continous covariate, and was interested in calculating an effect size and its 95% confidence interval (CI) using the marginal means. I noticed that JAMOVI has an option to calculate a Cohen's d and the 95% CI using the estimated marginal means but the CI provided differs from the one I calculated manually. Is there anyway of knowing what specific formula JAMOVI is using to conduct Cohen's d and the 95% CI using estimated marginal means? Also, Is it calculated using the standard error for the estimated marginal means?

Thanks

Francisco
Francisco
 
Posts: 1
Joined: Sat Dec 12, 2020 6:16 am

by jonathon » Sat Dec 12, 2020 6:49 am

hi francisco,

jamovi makes use of the eff_size() function from the emmeans package to calculate these:

https://rdrr.io/cran/emmeans/man/eff_size.html

cheers

jonathon
User avatar
jonathon
 
Posts: 1760
Joined: Fri Jan 27, 2017 10:04 am


Return to General