This is a repost of an article originally written and published by Peter Borden, and which was published on the blog of the now defunct social analytics company, SumAll. I came across this article back when Peter wrote it in 2014, and I found it to be an absolutely essential part of the discourse in the A/B testing industry. And so I wanted to re-publish the original article, since the original link is now dead, to help preserve its educational value for anyone interested in learning about A/B testing.