How many people are poor, and how fast are they leaving poverty? The data, if it exists at all, can be conflicting. The World Bank estimates that 25 percent of the people in the developing world live on an income of less than $1.25 a day (that's the threshold of absolute poverty defined by the lowest poverty lines in developing countries), down from about 40 percent in 1992. However, some other economists argue that absolute poverty is much lower (under 5 percent in 2010), and has declined much faster. Two economists who share that latter view make their case by going to an out-of-this-world source: nighttime views taken by NOAA weather satellites. They reason that the more lights that are on, the more developed a region has become. Read their research paper "Lights, Camera ... Income!: Estimating Poverty Using National Accounts, Survey Means And Lights" at VOX by going to tbtim.es/lights.