A revealing map of the world’s most and least ethnically diverse countriesEthnicity, like race, is a social construct, but it's still a construct with significant implications for the world. How people perceive ethnicity, both their own and that of others, can be tough to measure, particularly given that it's so subjective. So how do you study it? When five economists and social scientists set out to measure ethnic diversity for a landmark 2002 paper for the Harvard Ins
