With Facebook Home, mobile UX is more important to the company than ever. But even with such high stakes, Facebook doesn't let data dictate design. "We try to never deliver any reports ever, if possible," says Nate Bolt, who is in charge of design research at Facebook. "Reports can't attend meetings and they can't argue in favor of their findings. They die in the wastebasket immediately. So we'll bring up some data in a session, we brainstorm on a whiteboard, absorb some of the human patterns of the people that are using this stuff, and then incorporate that in our next build.