The low female participation in the North seems to reflect strong cultural and religious factors and less the socioeconomic status concerns which are stronger in the more developed and educated South and West. The main data sources are ILO (relatively aggregate data), a household survey by IHDS (latest data is 2005 with about 40 000 observations), and the NSSO household survey (every five years, latest 2012 with about 150 000 observations each year). The NSSO sample covers both informal and formal work.