The United Nations, for example, has embraced a series of ambitious ‘Sustainable Development Goals’ for 2030. But development experts are starting to call attention to a problem: we often don’t have the data we would need to figure out whether those goals have been met. Are we succeeding in reducing the amount of domestic violence suffered by women? If few countries have chosen to collect good enough data on the problem to allow for historical comparisons, it’s very hard to tell.11
