Imagine the perfect dish of spaghetti. Now imagine eating it every night. Or, once youve developed the perfect recipe, you keep trying variations that never taste quite as good as the original. Too little or too much variation kills our appetites. Examining and managing variation is a fundamental task of quality improvement. We can distinguish between variation in our processes of work and in the outcomes of our work. In either case, variation can be useful or harmful. How can we understand when variation is desirable and when it is not? The solution lies in determining whether the variation you see serves a useful purpose.