# $\eta^2$ and Cohen's $d$

After conducting a one way repeated measures ANOVA, I obtained the following value for eta squared=0.2861 (28.61%) and for Cohen's d =1.25

Cohen's guideline for effect's size: Small: 0.01; Medium: 0.059; Large: 0.138;

I understand that 28.61% of the independent var influenced the dependent var. How do I interpret my results?

1) Can we deduce that it is a large effect size by referring to eta-squared and cohen's d?

2) I have manually calculated the output by referring to my descriptive IBM SPSS statistics output.Kindly advise if there is a way to obtain cohen's d and eta-squared directly in the IBM SPSS output.

Thanks

I think what complicates the analysis of the effect size(s) here is the repeated measures (or within-subjects) design. Because of this, the calculation of the effect sizes might be different from simple one-way ANOVA. This article compares different effect sizes for within- and between-subject designs. At the end of the article you will see that, it suggests, for within-subjects designs, "effect sizes that control for intra-subjects variability ($\eta^2_p$ and $\omega^2_p$), or that take the correlation between measurements into account (Cohen's dz)" (Lakens, 2013).
I am not an SPSS user but as far as I understand SPSS already reports partial eta-squared ($\eta^2_p$). Here is an example of how to do ANOVA with repeated measures using SPSS (it also shows how to get effect size).