These challenges make new kinds of data — information that can be gathered indirectly using algorithms and novel sources — particularly valuable. Google searches and Twitter and Facebook posts, which are very useful in the United States, are unlikely to help us in Kibera or Dhaka, Bangladesh. But the core idea behind these sources of data — measuring without asking people directly — can be enormously helpful.
Nighttime luminosity tells us not just about electrification but also about economic activity more broadly, and statistical work shows it reliably correlates with economic performance. North Korea is not the only country where satellite photos tell a story that differs from the one told by official data. A seminal paper in the American Economic Review found estimates of income growth in many places that differed from official data by as much as three percentage points annually.