
James Stevenson thinks this is interesting:
This is a onesided hypothesis test for a proportion using two samples, and it can be run using a two sample ztest. If I use quota sampling and force the sample size of each group to be the same, or N = N_{1} = N_{2}, then the test statistic is a zstatistic,
where is the average of
From
 3 CONSERVATIVES, LIBERALS, AND OTHER POLITICAL PAWNS: HOW TO GAIN POWER AND INFLUENCE WITH SAMPLE SIZE CALCULATIONS
 from Beyond Basic Statistics: Tips, Tricks, and Techniques Every Data Analyst Should Know
 Publisher: John Wiley & Sons
 Released: May 2015
Note
Here's a good explanation of the formula for calculating sample size for A/B tests.
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