From Peter Drucker’s The Five Most Important Questions You Will Ever Ask About Your Organization,

My friend Philip Kotler, a professor at Northwestern University, points out that many organizations are very clear about the value they would like to deliver, but they often don’t understand that value from the perspective of their customers. They make assumptions based on their own interpretation. So begin with assumptions and find out what you believe your customers value. Then you can compare these beliefs with what customers actually are saying, find the differences, and go on to assess your results.