Business in the 21st century is being redefined by a data-driven revolution. Take the MIT Media Lab’s experiment to see whether it could estimate retail sales performance on “Black Friday,” the day following the US Thanksgiving holiday. Instead of waiting for data from the stores themselves, they used location data from mobile phones to infer how many people were in the parking lots of major retailers. Combining this with data on average spend per shopper enabled them to estimate a retailer’s sales, even before the company had recorded it themselves.