Satellite Images Can Pinpoint Poverty Where Surveys Can’t

By SENDHIL MULLAINATHAN

An explosion of data has already changed how we market products and politicians. Now a similar innovation is beginning to change how we combat poverty around the world.

Consider an unlikely problem: finding the poor. Even in a world riddled with poverty, nearly every government, nonprofit and aid agency struggles with this issue. Where in Kigali should the Rwandan health ministry place a new health clinic? Which rural districts in India should receive rice at subsidized prices? All these decisions require not just knowing poverty exists, but pinpointing areas of greatest need.

But until very recently, the data commonly used to answer these questions came almost exclusively from countrywide surveys, which are expensive and logistically challenging. It is very difficult to randomly sample people in the rural areas of Bihar in India or in a slum like Kibera in Nairobi, Kenya, where even just mapping the streets is its own project.

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.

Take the case of measuring the most basic of economic variables: gross domestic product. The numbers can be unreliable in countries where the statistical infrastructure is weak, the informal businesses do not want to be tracked and the numbers may be manipulated. Morten Jerven, an economist at Simon Fraser University, argues in his book, “Poor Numbers,” that for many African countries the lack of quality data impedes development.

To see how questionable official data can be, consider that in 2015 North Korea released a budgetary report claiming its economy had grown by roughly 225 percent. To verify this dubious economic miracle, we can turn to NASA, which has produced revealing nighttime satellite images. One image shows an ocean of lights in South Korea and China.

It also shows a vast darkness between them, depicting the grim reality of North Korea, where night lighting is a rare luxury. If North Korea is experiencing an economic miracle, it is a purely daytime affair.