statsmodels.stats.proportion.power_proportions_2indep¶

statsmodels.stats.proportion.
power_proportions_2indep
(diff, prop2, nobs1, ratio=1, alpha=0.05, value=0, alternative='twosided', return_results=True)[source]¶ power for ztest that two independent proportions are equal
This assumes that the variance is based on the pooled proportion under the null and the nonpooled variance under the alternative
 Parameters
 diff
float
difference between proportion 1 and 2 under the alternative
 prop2
float
proportion for the reference case, prop2, proportions for the first case will be computing using p2 and diff p1 = p2 + diff
 nobs1
float
orint
number of observations in sample 1
 ratio
float
sample size ratio, nobs2 = ratio * nobs1
 alpha
float
in
interval
(0,1) Significance level, e.g. 0.05, is the probability of a type I error, that is wrong rejections if the Null Hypothesis is true.
 value
float
currently only value=0, i.e. equality testing, is supported
 alternative
str
, ‘twosided’ (default
), ‘larger’, ‘smaller’ Alternative hypothesis whether the power is calculated for a twosided (default) or one sided test. The onesided test can be either ‘larger’, ‘smaller’.
 return_resultsbool
If true, then a results instance with extra information is returned, otherwise only the computed power is returned.
 diff
 Returns
 results
results
instance
orfloat
If return_results is True, then a results instance with the information in attributes is returned. If return_results is False, then only the power is returned.
 powerfloat
Power of the test, e.g. 0.8, is one minus the probability of a type II error. Power is the probability that the test correctly rejects the Null Hypothesis if the Alternative Hypothesis is true.
Other attributes in results instance include :
 p_pooled
pooled proportion, used for std_null
 std_null
standard error of difference under the null hypothesis (without sqrt(nobs))
 std_alt
standard error of difference under the alternative hypothesis (without sqrt(nobs))
 results