The popular phrase "you can't manage what you don't measure" points to the truth that a manager must know what his division is doing in order to properly guide and administer it. In the case of Southwest Airlines, estimated time of arrival (ETA) was improved by streamlining processes from aircraft maintenance to guest service. Sears improved personalized promotions by using data to identify important customer behaviors. In all of these examples, executives had to examine large data sets or "big data" and review the analysis to make decisions based on "analystics."