Over the past two hundred years, poor countries have become faster at adopting the technologies of rich countries. So why is it, the economist asks, that poor countries have remained poor, by and large? The answer, Diego Comin says, is that poor countries use technologies less intensely: fewer people use less advanced computers less often. To find out why – finance, institutions, geography? – Diego amasses data to measure the diffusion of technologies over two centuries. Compiling a big data set to study the drivers of technology adoption – this is new economic thinking.