statsmodels.stats.weightstats.CompareMeans.zconfint_diff¶

CompareMeans.zconfint_diff(alpha=0.05, alternative='two-sided', usevar='pooled')[source]¶

confidence interval for the difference in means

Parameters:¶

alpha : float¶

significance level for the confidence interval, coverage is 1-alpha

alternative : str¶

This specifies the alternative hypothesis for the test that corresponds to the confidence interval. 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 : str, 'pooled' or 'unequal'¶

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

Returns:¶

lower, upper – lower and upper limits of the confidence interval

Return type:¶

floats

Notes

The result is independent of the user specified ddof.