A/B testing is an essential component of large scale online services today. So essential, that every worth mentioning online business is already doing it. A/B testing is also used in email marketing by all major online retailers. The Obama for America data science team received a lot of press coverage for leverage data science, especially A/B testing during the presidential campaign.
This is a companion discussion topic for the original entry at https://blog.datasciencedojo.com/type-i-and-type-ii-errors/