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Cohen's d does not correct for multiple comparisons

I am performing a mixed 2x2 ANOVA and when I explore the effect sizes of the post-hoc test t, there is a note: "Cohen's d does not correct for multiple comparisons". See attached file of post hoc comparisons, I am interested in Post-pre comparisons of both groups.

I was wondering if It would be correct to perform a dependent t test with the data of each group in order to obtain the effect size corrected. See attached file of paired samples t-test.

Thanks in advance.


  • I have been thinking about it and I would like to express one possible idea, it would be great if someone could help me.

    I have noticed that JASP compute Cohen's d by the formula d = t/sqrt(n), isn't it?

    Then, if the post-hoc test reports the t value and I know the n, it would be correct to calculate the Cohen'sd using the above formula?

    I accept any suggestion.

    Thanks in advance.

  • Hi Vicente,

    I'm not an expert on frequentist methods for multiplicity correction. Have you Googled this? It does seem reasonable -- a little ad-hoc, but then again, it is a frequentist procedure :-) and there may be a rationale.



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