Definition
GEO_NG1990 (V101_NG1990) indicates the region of Nigeria where the respondent was interviewed. DHS regions in the 1990 Nigeria survey are equivalent to grouped states.
Other sample years have their own sample-specific geography variables. There are also integrated variables, GEO_NG2003_2013 and GEOALT_NG2008_2013, that provide spatially consistent units over time. The 1990 Nigeria sample is excluded from GEO_NG2003_2013 and GEOALT_NG2008_2013 due to inconsistent boundaries.
A GIS map for GEO_NG1990 (in shapefile format) can be downloaded from the DHS Program Spatial Data Repository [URL omitted from DDI.] Boundaries page.