When your company is doing well, revenue is pouring in, and your stock is rising, how do you know if you could be doing better? How can you tell which of your management practices are making the difference and which are merely doing no visible harm? Benchmarking is the obvious answer, but not by comparing poor companies with good ones. The way to get at this problem is to compare good companies with even better ones.

A version of this article appeared in the July–August 2007 issue of Harvard Business Review.