In GPW data that is comprised of 2.5 arc min cells, are the cells georeferenced from the cell center, or right/left and upper/lower corner? I understand that xllcorner and yllcorner give the starting lat/lon for overall grid position, but are the cell data themselves valued at each lower left corner?
The GPW data are referenced to the cell center. The grid description does reference the corner coordinates but the data are modeled at the center of the cell (1/2 of the resolution in both dimensions or 0.02083333 degrees).