Study calls for review into census capture of 'mixed' populations

Current methods of capturing mixed race/ethnicity populations in global censuses are unreliable, and must be reviewed to ensure increasingly diverse populations are effectively reported, a study published today in Ethnic and Racial Studies suggests.

The study investigated three current methods of mixed population capture: 'exact combinations' of interest (used in England and Wales), 'open response' (Scotland and Northern Ireland), and 'multi-ticking' across population categories (the USA and Canada), to assess the optimal approach.

Analyzing the effectiveness of each method in terms of its stated aims, consistency of findings in the same subjects across censuses, and overall capture of mixed races and ethnicities, the study reveals serious quality problems with all three approaches.

The considerable variation between countries' demography and measurement methods led the author to urge caution in proposing one overall 'gold standard' method of capture. Instead, it was suggested that 'multi-ticking' should be continued in the US and Canada, with clearer instructions for respondents, and extensively trialled as a potential alternative to the 'exact combinations' method in England and Wales, given its effectiveness in capturing racial/ethnic variation.

The mixed racial/ethnic group is one of the fastest growing in both the UK and North America. In the 2011 England and Wales Census, for example, 1.2 million persons of 'mixed/multiple' ethnicity were recorded, up from around 670,000 in 2001. With experts widely expecting substantial increases in the size of the mixed population in western countries in the coming years, the need for reliable, accurate data is of growing significance.

As the author of the study, Peter J. Aspinall, commented: "The presence of a growing mixed population in most countries is a recent phenomenon or one made more visible through measurement. This raises challenges for the capture of this population in censuses and surveys.

"The methods used in many of these censuses have, to date, failed to reliably do so. With the next round of global censuses fast approaching, the need to identify the best methods for capturing what are increasingly complex mixes is all the more pressing."