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. Ifunequal
, then Welch ttest with Satterthwait degrees of freedom is used
- alpha
- Returns:
- lower, upper
floats
lower and upper limits of the confidence interval
- lower, upper
Notes
The result is independent of the user specified ddof.