Although the ONC methodologies are principally concerned with identifying and adjusting for census under-enumeration, part of the CCS interview was also aimed at identifying any potential overcount in the 2001 census, that is persons incorrectly enumerated as resident at more than one address. A number of factors built into the process helped to reduce the chance of over-enumeration. These include simplification of definitions and clarification of who should be included and where. The expectation is that over-enumeration will only occur accidentally. Examples of such possibilities include second homes and children from broken homes living a proportion of time with each parent. Analysis of responses to the CCS indicated that the level of overcount in the 2001 census was negligible - less than 0.1 per cent of the population were estimated to have been counted twice. This is well within the estimated precision of the ONC estimates (plus or minus 0.2 per cent for England and Wales) and has therefore been taken as not significant in calculating the ONC estimates.

This page last revised: 01 November 2005