Contrast Effect size

Evahoog

Hi,

I've used contrast testing (Difference) for a RM ANOVA with 3 levels (T0,T1,T2).

It showed the effect size (cohens d) with JASP, but the reported effect sizes are different from what I calculated by myself, using the formulae (Mean T1- Mean T0)/sd.

For example:

• my calculation: -0.280
• JASP: -0.230

I've used the exact same input.

Can someone explain me how cohens d of the contrast testing (difference) is calculated in JASP?

Then I can figure out the issue in my own calculations.

Thanks!

Eva

EJ

Hi Eva,

Have you computed the same result in a different program (R?). You can also give ChatGPT a shot. If you can't get to the bottom of this please provide a concrete data set so it is easier to discuss the matter.

Cheers,

E.J.