Cohen’s f2 : how do you calculate it ?

[JB Lanfranchi]

Hi,

I would like to know how you calculate the Cohen's f2 in GSCA Pro. I tried with
the formula :

f2 = (R2_inc - R2_exc)/(1 - R2_inc)

If i want to know the effect size of A on B in this model :

A -> B

C -> B

D-> B

I calculate two models: one with A (R2_inc) and one without A (R2_exc). But i don't find the same result in "F square value". Should I use the factor scores from the full model rather than doing two models?

Cheers,

Jean-Baptiste