Eric Garcetti, the mayor of Los Angeles, has big ambitions but knows he must first master the small stuff. He's also a polymath who relies heavily on data and new technologies. Could this be what modern politics is supposed to look like?

The U.S. president is often called the "leader of free world." But if you ask an economist or a Constitutional scholar how much the occupant of the Oval Office matters, they won't say much. We look at what the data have to say about measuring leadership, and its impact on the economy and the country.