In pursuit of tough questions

PROFESSOR Roberto Rigobon's formula for advancing human knowledge is fairly easy to remember: Don't do easy.

The dauntless pursuit of big and meaningful problems and an obsession with understanding the limitations of data led Professor Rigobon and his collaborator Alberto Cavallo to take on that entrenched institution known as the consumer price index (CPI). The result was the Billion Prices project, an audacious real-time cost-of-living gauge that has lifted inflation measurement into the Internet age.

Here's the kicker: Prof Rigobon is not done. By his own reckoning, the CPI was the easiest on his to-do list.