1）Google has a very good class for AB testing below. It’s on Udacity. If you just want see an example of sample size calculation, this particular part will guide you through the process with click through rate as an example. lesson 1 part 23: quiz ‘Calculating Number of Pages Views Needed’. https://classroom.udacity.com/courses/ud257/lessons/4018018619/concepts/40043987060923 Here is some simple key notes from this class to refer to. https://medium.com/@jinfenghuang/a-b-testing-8e349afeb370
2） A/B Testing for Business Analysts （short）
https://classroom.udacity.com/courses/ud979
3） Business application plus sql https://community.modeanalytics.com/sql/tutorial/sql-business-analytics-training/