In order to see any progress in a process, first we have to make metrics to measure that progress.
What makes a good metric? A good metric should measure something that is actually important to the goal of the process improvement initiative. If you want to increase customer satisfaction then the height of your average employee is probably not going tell you a whole lot about that. Instead, maybe try lead time.
One more thing that should be considered is cost of the measurement. Measuring customer satisfaction by constantly putting out paid surveys can be expensive. Finding out there is a inverse correlation between lead time and customer satisfaction through a paid survey should be enough to use lead time as a good metric to use for an initiative to increase customer satisfaction.