statsmodels.stats.proportion.samplesize_proportions_2indep_onetail¶

statsmodels.stats.proportion.
samplesize_proportions_2indep_onetail
(diff, prop2, power, ratio=1, alpha=0.05, value=0, alternative='twosided')[source]¶ required sample size assuming normal distribution based on one tail
This uses an explicit computation for the sample size that is required to achieve a given power corresponding to the appropriate tails of the normal distribution. This ignores the far tail in a twosided test which is negligible in the common case when alternative and null are far apart.
 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
 power
float
Power for which sample size is computed.
 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. In the case of a onesided alternative, it is assumed that the test is in the appropriate tail.
 diff
 Returns
 nobs1
float
Number of observations in sample 1.
 nobs1