A comparison for 1995, 2005, and 2011 reveals large discrepancies in the two main sources of population data, the censuses and the civil registration system. Possible reasons and implications of the observed discrepancies are discussed, and suggestions are made for actions and policies that might help improve data quality. This analysis suggests that the numbers recorded by the Public Authority for Civil Information (PACI) are likely to be relatively more reliable and valid than the census. However, a conclusive statement about this requires additional objective analysis. A system of post-enumeration sample surveys may be established as a usual mechanism for checking the accuracy of census data. Also, special studies designed to ensure the accuracy of PACI data should be conducted periodically.