Everyone knows you have to listen to your customers and find out what they want. Each day, hundreds, if not thousands, of focus groups meet to try to discern customers’ needs and create products or services that will address them. But few companies fully capitalize on those opportunities. Why? Because they essentially ask people, “How can we make our product or service better?” That approach will result in incremental improvements, but it hardly leads to real advances. Here’s a method for picking your customers’ brains that reflects a subtle shift in approach—one that can yield major advances.

A version of this article appeared in the September 2001 issue of Harvard Business Review.