Enhancing the population census: A time series for sub-national areas with age, sex, and ethnic group dimensions in England and Wales, 1991-2001

Ethnicity data from successive censuses are used to compare population change. This paper shows that such comparisons are often impossible, wrong or misleading. Distortions become more severe as the scale of areal units becomes smaller. The paper outlines the four main sources of confusion and applies solutions for England and Wales for 1991-2001: (1) classifications, including ethnic group and age, changed between censuses; (2) non-response varies between ethnic groups, areas and ages and its treatment differs in each census; (3) the census population base changed, counting students at their home address in 1991 and at their educational address in 2001, and being taken on a different date in each year; (4) geographical boundaries used for standard census outputs changed. Each of these factors operates differentially on the outcome. © 2009 Taylor & Francis.