I am comparing the same continuous variable (age) for two different groups. I would like to know if this variable has significant differences between the groups. As I have high sample sizes for both groups, I am also calculating Vargha and Delaney's A to obtain the effect size. The thing is I would like to know if there exist thresholds to know if the effect size is small, medium or large as it happens for example for Cramer's V.

Thank you in advance.

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1 Answer 1


Interpretation guidelines are given in Vargha and Delaney's paper:

Vargha, A. and H.D. Delaney. A Critique and Improvement of the CL Common Language Effect Size Statistics of McGraw and Wong. 2000. Journal of Educational and Behavioral Statistics 25(2):101–132.

Of course, these interpretations have no universal authority. They are just guidelines based on the judgement of the authors, and are probably specific to field of study and specifics of the situation under study.

You might see the original paper for their discussion on the derivation of these guidelines.


  0.56 – < 0.64
> 0.34 –   0.44


  0.64  – < 0.71
> 0.29  –   0.34


≥ 0.71
≤ 0.29

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