You know less than you think you do - about what makes you healthy, what makes you rich, who you should date, where you should live. You know less than you think you do about how to raise your children, or, for that matter, whether you should have children in the first place. Seth Stephens-Davidowitz showed how big data is revolutionising the social sciences. He shows how big data can help us find answers to some of the most important questions we...