Progress on achieving the Sustainable Development Goals requires high quality measurement. Too few attempts are made to assess the accuracy of existing measurements and how it changes over time. We compare household counts and electrification rates for the Agincourt Health and Demographic Surveillance Site (HDSS), as measured in the 1996, 2001 and 2011 national censuses and in the database of the HDSS. The household measurements in the two systems agree within a few percentage points in 2001 and 2011 but show much bigger divergences in 1996. The population counts also show impressive agreement, with perhaps some over-enumeration of older males in the national census. Overall, survey and census information seem to provide accurate measures of population access to electricity.