The paper is an overview of diversity in history, starting as far back as the societies in classical Ancient Europe and traditional non-European societies, where differentiation was basically between the enslaved and free population and the out-of-caste in India. With the end of slavery the...

"We show that much of the recent reported decrease in interstate migration is a statistical artifact. Before 2006, the Census Bureau's imputation procedure for dealing with missing data inflated the estimated interstate migration rate. An undocumented change in the procedure corrected the...