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statsmodels.stats.weightstats.CompareMeans.ztest_ind

CompareMeans.ztest_ind(alternative='two-sided', usevar='pooled', value=0)[source]

z-test for the null hypothesis of identical means

Parameters:

x1, x2 : array_like, 1-D or 2-D

two independent samples, see notes for 2-D case

alternative : string

The alternative hypothesis, H1, has to be one of the following ‘two-sided’: H1: difference in means not equal to value (default) ‘larger’ : H1: difference in means larger than value ‘smaller’ : H1: difference in means smaller than value

usevar : string, ‘pooled’ or ‘unequal’

If pooled, then the standard deviation of the samples is assumed to be the same. If unequal, then Welsh ttest with Satterthwait degrees of freedom is used

value : float

difference between the means under the Null hypothesis.

Returns:

tstat : float

test statisic

pvalue : float

pvalue of the t-test

df : int or float

degrees of freedom used in the t-test

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