Sendhil Mullainathan

The problem with data is that it says a lot, but it also says nothing. 'Big data' is terrific, but it's usually thin. To understand why something is happening, we have to engage in both forensics and guess work.

No one would say, 'Hey, I think this medicine works, go ahead and use it.' We have testing, we go to the lab, we try it again, we have refinement. But you know what we do on the last mile? 'Oh, this is a good idea. People will like this. Let's put it out there.'

Many of the things that I have written on have focused, at least a big part of the story, on adolescents. I think that in that period of life, so much happens, and it's the period of life where you're forming into an adult. In certain ways, you're already an adult and in certain ways you're still a kid.

Every time you log in to Facebook, every time you click on your News Feed, every time you Like a photo, every time you send anything via Messenger, you add another data point to the galaxy they already have regarding you and your behavior.