stats.proportion.proportion_effectsize()

statsmodels.stats.proportion.proportion_effectsize

statsmodels.stats.proportion.proportion_effectsize(prop1, prop2, method='normal') [source]

effect size for a test comparing two proportions

for use in power function

Parameters:	prop1, prop2: float or array_like :
Returns:	es : float or ndarray effect size for (transformed) prop1 - prop2

Notes

only method=?normal? is implemented to match pwr.p2.test see http://www.statmethods.net/stats/power.html

Effect size for normal is defined as

1	2 * (arcsin(sqrt(prop1)) - arcsin(sqrt(prop2)))

I think other conversions to normality can be used, but I need to check.

Examples

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>>> smpr.proportion_effectsize(0.5, 0.4) 0.20135792079033088 >>> smpr.proportion_effectsize([0.3, 0.4, 0.5], 0.4) array([-0.21015893,  0.        ,  0.20135792])