To provide an accurate national estimate of the population, the One Number Census project adjusted the results of the 2001 Census to take account of those missed. A key element in this process was the Census Coverage Survey. The results of the Census were matched against those of the Census Coverage Survey, identifying the number and characteristics of those missed in the Census. This information was used to amend the census results to reflect those omitted in the original count. For areas not included in the Census Coverage Survey, standard statistical techniques were applied to estimate the undercount. Administrative registers and demographic estimates were used to quality assure the adjusted population counts.