“The customer is also at the center of how we analyze and manage performance metrics. Our emphasis is on what we call controllable input metrics, rather than output metrics. Controllable input metrics (e.g., reducing internal costs so you can affordably lower product prices, adding new items for sale on the website, or reducing standard delivery time) measure the set of activities that, if done well, will yield the desired results, or output metrics (such as monthly revenue and stock price). We detail these metrics as well as how to discover and track them in chapter six.”