Cohen’s h Effect Size

Cohen’s h can be used as a measure of the size of the effect between two proportions (i.e. p1p2).

2 arcsin √p1 – 2 arcsin √p2

We calculate Cohen’s h in Excel using the formula

=2*(ASIN(SQRT(p1))-ASIN(SQRT(p2))).

When no other information is available, the guidelines for the size of this effect are

h = .2: small effect, h = .5: medium effect, h = .8: large effect

Reference

Wikipedia (2020) Cohen’s h
https://en.wikipedia.org/wiki/Cohen%27s_h

2 thoughts on “Cohen’s h Effect Size”

  1. You could drop my question; I realized I had a table to percentages, not proportions, and that is why the SQRT(p1) were above 1.

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  2. The ASIN function requires a number between -1 and 1. Do you know how to calculate this if the square root of the proportion is more than 1 (i.e., the SQRT(p1) or SQRT(p2) part of the equation)?

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