If it is not too much work, I would recommend that you run the analysis twice — once with GPW, and a second time with GRUMP. This would give you an idea of the variability in the two models of population. However, please note that the alpha version of GRUMP has a tendency to over allocate population from rural areas to urban areas, so we have modified the algorithm for the beta version that we are working on.
For additional information about GPW and GRUMP, please see the links below :
Documentation for GPW is available at:
and for GRUMP at:
More generally, information on both projects is linked from: