Income is an important correlate for numerous phenomena in the social sciences. But many surveys collect data with just a single question covering all forms of income. This raises questions over the reliability of the data that are collected. Issues of reliability are heightened when individuals...

International surveys of educational achievement and functional literacy are increasingly common. We consider two aspects of the robustness of their results. First, we compare results from four surveys: the Trends in International Maths and Science Study, the Programme for International Student...