The document discusses how retailers can create competitive advantage by leveraging big data. It notes that today's shoppers generate vast amounts of data through their online and in-store activities. It then outlines three key reasons why retailers should focus on big data: (1) the amount of data being generated is huge and growing rapidly, (2) big data can significantly increase retailer profits and productivity, and (3) big data analytics has become critical to competition between retailers. The document then introduces McKinsey's Consumer Marketing Analytics Center (CMAC), which helps retailers integrate diverse data sources, generate insights from big data, and embed these insights into decision-making.