Thursday, May 21, 2009

A/B and Qualitative User Testing

Recently, I worked with a company devoted to A/B testing. For those of you who aren't familiar with the practice, A/B testing (sometimes called bucket testing or multivariate testing) is the practice of creating multiple versions of a screen or feature and showing each version to a different set of users in production in order to find out which version produces better metrics. These metrics may include things like "which version of a new feature makes the company more money" or "which landing screen positively affects conversion." Overall, the goal of A/B testing is to allow you to make better product decisions based on the things that are important to your business by using statistically significant data.

Qualitative user testing, on the other hand, involves showing a product or prototype to a small number of people while observing and interviewing them. It produces a different sort of information, but the goal is still to help you make better product decisions based on user feedback.

Now, a big part of my job involves talking to users about products in qualitative tests, so you might imagine that I would hate A/B testing. After all, wouldn't something like that put somebody like me out of a job? Absolutely not! I love A/B testing. It's a phenomenal tool for making decisions about products. It is not the only tool, however. In fact, qualitative user research combined with A/B testing creates the most powerful system for informing design that I have ever seen. If you're not doing it yet, you probably should be.

A/B Testing

What It Does Well

A/B testing on its own is fantastic for certain things. It can help you:
  • Get statistically significant data on whether a proposed new feature or change significantly increases metrics that matter - numbers like revenue, retention, and customer acquisition
  • Understand more about what your customers are actually doing on your site
  • Make decisions about which features to cut and which to improve
  • Validate design decisions
  • See which small changes have surprisingly large effects on metrics
  • Get user feedback without actually interacting with users