The Surprising Power of Online Experiments

---

Getting the most out of A/B and other controlled tests

In the fast-moving digital world, even experts have a hard time assessing new ideas. Case in point: At Bing a small headline change an employee proposed was deemed a low priority and shelved until one engineer decided to do a quick online controlled experiment—an A/B test—to try it out. The test showed that the change increased revenue by an astonishing 12%.

That experience illustrates why it’s critical to adopt an “experiment with everything” approach, say Ron Kohavi, the head of the Analysis & Experimentation team at Microsoft, and Stefan Thomke, an HBS professor.

In this article they describe:

• How to properly design and execute A/B and other controlled tests
• Ensure test integrity
• How to interpret results and avoid pitfalls