The Census and social science
Written evidence submitted by CURDS (Centre for Urban and Regional Development Studies) (Census 27)
2021 Population Census
Declaration of Interest
0 CURDS has undertaken academic and policy-relevant research for 35 years, and the datasets from successive Censuses underpinned much of its geographical analysis. Some of this work was recently part of our contribution to the Spatial Economics Research Centre funded by two government departments plus the national social science research council. In this long-standing contribution to public debate and academic knowledge of CURDS research into spatial dynamics, far less would have been possible without the Census.
 How do social scientists use census data?
1 CURDS researchers use UK Census of Population data both directly in secondary data analysis to reveal the spatial patterns and processes at work in the British economy and society, and also indirectly to ‘benchmark’ our own primary research (ie. to validate the coverage by our survey of the total population of an area or group of particular interest). In this respect, research by CURDS is perhaps ‘representative’ of that carried out by many social and spatial scientists. The following paragraphs focus on more CURDS-specific considerations so as not to duplicate the inputs from the learned societies to which CURDS actively contributes.
2 CURDS researchers use the nearest alternative to the Census – datasets from the Annual Population Survey (APS) – but much of the specialist research for policy makers and others simply could not be done at all with this due to it not providing robust data at a sufficiently detailed area level. The irreplaceability of the Census across a wide range of CURDS research stems from its multiple and inter-linked value for
· analysing neighbourhood effects (eg. on child poverty), due to its local detail
· highlighting the situation of minority groups, due to its ‘sample’ nearing 100%
· separating multiple influences on outcomes, due to its wide subject coverage
· recognising the role of mobility in social and economic inequalities, due to its unique provision of fine-grain data on migration and commuting.
 What impact will the ending of the Census have on social science research?
3 For almost 30 years CURDS has defined Travel-to-Work Areas for the government by analysing each new Census commuting dataset, and now has beg u n research for Eurostat exploring the possibility of a ‘European standard method’ for defining labour market areas ; it would be incredible if the world-leading British research in this field could not be conducted in Britain in future, but this would be the case if the Census was discontinued .
4 CURDS research which relies on Census commuting data (among other datasets) made a prominent contribution to the recent urban and regional policy developments call ing for economic and housing po licy delivery at the functional economic area (FEA) scale that, for example, is invoked in relation to Local Economic Partnerships. As y et there is no established way to identify these economic ‘places’ in practice , although there is a consensus that the analysis of the Census commuting data is the single most important way forward to such definitions. Most importantly, the patterns observed by such analyses reveal change in the economic self-sufficiency of areas, with the consequence that these analyses need repeating to update understanding: this will not be possible if the key Census datasets no longer exist.
5 With a more academic emphasis, CURDS has been a major user of the Census Origin-Destination Statistics which include data on migration as well as commuting. These datasets are irreplaceable in measuring the flows between each geographical area and every other one in the country, right down to the neighbourhood scale. CURDS research has, for example, shown how migration can alter the social and economic profile of areas through, for example, ‘brain drain’ trends due to the northern cities being unable to retain the graduates from their universities.
6 It should always be remembered that the data collected in 2011 and any subsequent Census will be used for decades or even centuries into the future, just as the data from past Censuses are prized by researchers (along with the ever growing numbers of family historians). If there had been no Census in 2011 it would not be possible now or later to ‘go back and fill that gap’ in knowledge: we have a duty to future generations to collect data on the present, just as we rely on the data collection carried out in the past by our forbears.
 What alternatives to the Census would provide population and socio-demographic data of equivalent or higher quality?
7 The idea that there are effective alternatives to the Census is wrong.
Ø It is sensible to test some candidate alternatives, but this must be done without the expectation that at least one can replace the Census: the test should be "can an alternative provide the data the Census currently provides" and not "which is the best alternative, given that Census will be replaced"
Ø None of the proposed alternatives will provide the combination of small area detail and accuracy that make Census data the one essential data resource: the nearest alternative is APS but much specialist research for policy-makers and others simply could not be done at all with this due to it not providing small area data
Ø What makes the Census data absolutely irreplaceable is not the small area detail alone but its combination with a rich range of variables, all of which have been exhaustively evaluated to ensure they are the most important for policy-makers and other users: none of the alternative sources would provide data that can answer such a wide range of key questions about communities (whether these are communities defined in terms of neighbourhoods using small area data, or communities defined by dimensions such as religion, which means for example being unable to answer many questions on the equalities agenda
Ø An experiment was undertaken by ONS to see whether APS could provide the necessary data on commuting for updating official Travel-to-Work Areas (TTWAs) and it was found that this was very far from true: if the Census is not continued this updating will be impossible which will leaving policy-makers and many others without a resource they have had for many decades (in fact Eurostat is currently discussing the need for such definitions in all countries)
Ø The increasing ubiquity of GIS means that the need for small area data will continue to grow inexorably so any move away from providing such data could not be more bizarrely or detrimentally timed
Ø Much valuable policy-relevant research relies on the high level of consistency between decennial Censuses to understand change over time and this would be lost by shifting to data collected in different ways; a specialist case of this risk is the increasingly valuable Longitudinal Survey whose linkage of Census records provides a unique resource whose value increases with each decade
8 The only really robust alternative to a Census is provided by a register system such as those in Scandinavian countries where such systems are so familiar and trusted that there is also little public concern at considerable linkage between these systems and many other datasets. However there are considerable public qualms about such systems in the UK (and in fact there is no single unique personal identifier used across official datasets).
 What other existing sources of population and socio-demographic data could be improved upon?
9 The key limitation of alternative data sources such as ONS social surveys is their sample size, preventing data being made available for smaller geographical areas. The value of these sources derives from them providing ‘top up’ information between Census years so that aggregate trends can be identified. Reflecting on the way that such surveys were designed to complement the robust comprehensive audit of the national population that the Census provides periodically, it can be seen that the arguments which are made for dropping the Census are wrong.
Ø "Census data ‘out-of-date’ much of the time" – but most analyses for which Census is the only plausible data source are not of rapidly changing trends
Ø "Census is expensive" – averaged over 10 years it is not expensive, and then divided by its myriad uses makes it very low cost: almost certainly the options for replacement will cost at least as much over the decade and will add little by being more frequently available (see above) while being of far less use (see below) so overall of much less cost effective
Ø "Census information is increasingly difficult to collect" – in fact the signals from the 2011 Census are there was less of a problem than in 2001
Prof Mike Coombes on behalf of CURDS (Centre for Urban and Regional Development Studies) Newcastle University
30 November 2011