“…This makes the nighttime light-based measurement of ethnic disparity less desirable and satisfactory. However, the two problems may not be very severe, as many studies report that minority ethnic groups usually stay in their traditional homelands due to attachment to native land and being unaware of the greater economic opportunities available with migration (Poston, Micklin, and Shu 1998;Yang 2007), and most of them tend to reside in border areas highly segregated residentially from the Han Chinese (Poston, Chang, and Dan 2006;Poston, Micklin, and Shu 1998). Even for those who migrate, they tend to prefer places within their traditional regions of residence; areas with similar languages, religions, and ethnic traditions (Yang 2007 To determine the reliability of the data, we conducted an accuracy assessment of the GREG data-set based on the following assumption: If the 1960s GREG data for ethnic population distribution is still accurate, meaning that each polygon in GREG data is homogeneous and just for that specific ethnic group, then for each administrative region such as a county, the estimated population for each ethnic group using GREG and LandScan (described below) within that administrative region should be consistent with the ethnic population census data within that administrative region.…”