It's not difficult to understand why cross-device measurement have become so important. Facebook commissioned a study earlier this year showing how consumers use multiple devices in everyday life. In fact, more than 60% of online adults in the U.S. use at least two devices daily and nearly one-quarter use three devices. Even Google has published multiple studies that suggest a high number of consumers start an activity on one device only and finish on another. Jennifer Wong gives us insight into reporting in a cross-device world.