Back when Zuckerberg was a but a tween and Twitter was yet a twinkle in anyone’s eye, the customer of a multivariate testing SaaS vendor ran an interesting promotional test: 20% off any purchase against buy one refrigerator and get another free. To everyone’s surprise, refrigerators flew out the door. Turns out, the Joneses found out about the deal and told the Smiths who came in on it with them. Each family went home with a half price fridge.
What a testament to the power of testing, we all said. Who knew you could move such a large item with such a promotion? What we all thought we learned was that you never know what you don’t know. And you’ll never know unless you test.

