The Census and social science - Science and Technology Committee Contents

3  Value of the census

29. Census data play a significant role in the research of most of the social scientists from whom we received evidence. In the words of the Institute for Fiscal Studies, the census is "the key source of information on population statistics".[20] A number of organisations highlighted the value of continuing to collect census data for:

·  the very high coverage achieved due to the legal obligation to respond;[21]

·  the longitudinal studies that have been taking place providing detailed information about the impact of changes across UK society;[22]

·  the level of detail achieved despite the wide geographical coverage;[23]

·  the fact that the census is a source of data independent of official information (ie information gathered by public bodies for their own specific purposes);[24]

·  the increasing difficulty of comparing data from different authorities;[25] and

·  the fact it provides a reference point based on a sample approaching the whole UK population.[26]

We will briefly consider each of these in turn.


30. Householders are statutorily required to complete a census form on behalf of those sharing their property, and to do so accurately. The Office for National Statistics expends considerable effort in ensuring that as many people as possible comply with this requirement. Of all the sets of social data listed in paragraph 20 above, only the census has a sample size significantly approaching the whole UK population. Population studies are often judged on their sample size: as size increases, potential bias due to sampling decreases.

31. The value of a nationally co-ordinated data-collection system was expounded by Professor Martin of the Royal Statistical Society:

    My personal view is that the independence of the census as a nationally consistent exercise is one of the great strengths that any replacement system would have to have. It would be exceedingly difficult to mandate organisations of different sizes and shapes, with different biases inherent in their populations, to produce something that you knew was using the same methodology in every place.[27]

A key advantage of the current system is that it produces a national dataset, at a fixed moment in time, that is consistent across the whole of the UK.


32. A key advantage of the census raised several times was that it provided a broad sample from which appropriate candidates could be selected to continue valuable longitudinal studies. Professor Blane, Deputy Director of the ESRC International Centre for Life Course Studies, considered that longitudinal studies required a large data context to be properly resourced:

    Britain remains the envy of the world in the richness of its longitudinal datasets. [The] 1946 birth cohort [...] have been tracked right across their lives and they are now in their 60s—my age. When you track people over that length of time, obviously, people drop out. What you need is a population count that tells you how representative the people left in these Longitudinal Studies are and what the directions of a selective bias might be. I do not see any other alternative than the census for that purpose.[28]

33. The British Library noted:

    Historic census data is used in combination with other sources such as the Registrar-General's Reports by historical demographers and social historians to:

·  Map changes in population spread over time

·  Track changes in housing, household composition and employment over time

    Census data can be combined with results from other surveys to present demographic change alongside attitudinal change. Examples include family and household composition, the change from manufacturing to service economy, journeys to work, changing household composition, changing housing conditions, and the use of domestic servants (including the more modern, 'help').[29]

Organisations such as the British Society for Population Studies raised the issue of examining trends over long period to see societal changes and future trends, information that—they argued—is currently available in reliable form solely through the census:

    For researchers, the key question is 'Is there an alternative data source with the range, detail and quality of information that the Census currently provides?' and not 'Which is the best alternative, given that Census will be replaced?'[30]

Detailed local information

34. Many submissions to our inquiry raised the value of the census in providing detailed information about local areas.[31] We were told that local authorities required the census to provide:

    Accurate local authority population estimates as a key element of financial settlements.

    Accurate estimates of particular populations eg children of school age and pre-school age, the number of elderly, the number suffering from ill health.

    Detailed information on local areas to inform needs and priorities, and to find out the individual needs of particular areas. The sorts of information that local authorities find useful at local level include single parent households, old people living alone, housing data (including overcrowding), unemployment, qualifications of residents, health issues, and employment and commuting data.[32]

35. The Joseph Rowntree Foundation emphasised the ease with which the data could be used to compare different geographical areas:

    It is unique because it covers everyone at the same time and asks the same core questions everywhere. This makes it possible to compare different parts of the UK, Local Authorities and even smaller area statistics on many of the range of variables collected.[33]

36. Of particular interest was the information on household composition: the Royal Statistical Society pointed to the ability to "create bespoke cross tabulations of census variables and to analyse household structures".[34] We were told that the ability to look at fine detail was made possible due to the immense sample size of the census as a whole. John Stillwell and Oliver Duke-Williams of Leeds University said:

    The ending of the census will therefore have a pronounced impact on research on migration and commuting behaviour from a geographical perspective because it is very unlikely that there would be any alternative mechanism or combination of methods that would provide the attribute detail for small areas such as output areas or super output areas across the whole country.[35]

37. The British Library highlighted the use of census data by a range of third sector organisations:

    Census data made available free of charge via the Neighbourhood Statistics service is relied on by voluntary and community organisations, self-help groups and other bodies active at local levels to provide them with a detailed picture of local populations and socio-economic conditions in small areas. This information is then used to identify need, plan services and support funding bids and campaigns.[36]

38. The British Library also told us that the census had the potential to "provide greater representation of marginalised groups" as the near-universal coverage ensures that they are counted.[37] Evidence from the Salvation Army supported this; it uses census data to provide the organisation with "a foundation of what a community consists of".[38] This was not an uncommon perception among witnesses.


39. The Joseph Rowntree Foundation pointed out a number of surveys carried out in the UK:

·  The Labour Force Survey (LFS),

·  The Longitudinal Study of Young People in England (LSYPE)

·  Households Below Average Income (HBAI)

·  The Annual Population Survey (APS)

·  The Family Expenditure Survey (FES)

·  Health Survey for England (HSE)

·  Families and Children Study (FCS)

·  Growing Up in Scotland (GUS)

·  Millennium Cohort Study (MCS)[39]

These surveys are conducted mainly to provide specific information necessary for the formulation of particular policies. Concerns raised about such sources, in comparison to the census, include inadequate detail,[40] a lesser geographical coverage[41] or a lack of comparators to enable the aggregation of information in order to produce studies of greater depth.[42] Moreover, the provision of census data is something that has been done for so long that there is less suspicion among the populace about the motives for data collection and greater willingness to provide data, which is likely to mean that census data is more representative and more accurate than is obtainable from smaller-scale, more focused surveys.[43]


40. The large dataset produced by the census is valuable in that it can be used to adjust other surveys and studies which may, due to their more voluntary nature or because the participants do not entirely trust the purposes to which the information may be put, be less accurate. The British Academy argued for the value of census data as a central reference point against which other social data might be judged.[44]

41. The Joseph Rowntree Foundation described the role of the census as a lynchpin between other datasets:

    the census data enriches many other datasets by linking with them and therefore really enhancing the analysis possibilities. For example, the ONS Longitudinal Study (LS) is a data set comprising linked census and event records for 1% of the population of England and Wales (about 500,000 people at any one census). It was set up in 1974 to address problems with the adequacy of occupational mortality data, and the lack of longitudinal fertility data, but since then it has been used to address a wide range of other research questions.[45]

Disadvantages of reliance on census data

42. However, the fact that the census plays such a key role as a research tool may have a disadvantage. Professor Les Mayhew, Cass Business School, suggested that the census had a stifling impact on research in social sciences and that discontinuing it 'would lead to a period of huge innovation in the research community'.[46] This was not a perspective shared by the Economic and Social Research Council (ESRC) or the ONS.[47]

43. We appreciate the central role that census data has played for social scientists. The main reasons for its importance for academia are datasets that can be used across many years, continuing longitudinal studies and a central reference point with which other data may be compared. However, Professor Mayhew's concern that social scientists may turn to the census data simply because it is there rather than because it provides the best data source for the research in hand was not convincing. However, we do recommend that the ESRC ensures that, among those researchers it funds, there is no over-reliance on census data to the exclusion of more appropriate data sources, or such use that stifles the development of innovative means of gathering or utilising social data.


44. The problem with the census most frequently mentioned to us was that census data may quickly go out of date due to the gaps between census-taking, exacerbated by the lengthy data processing after the data-gathering exercise.[48] The advantages of the census— size and comprehensiveness—are diminished when the data is not utilised until almost two years later, especially in areas such as London, where the population is highly mobile and changeable.

45. Professor Mayhew strongly argued that policy decisions needed to be made from data that is both current and accurate.[49] The Office for National Statistics itself questioned the value of a census that takes place only every ten years of a population that is increasingly mobile: "This can be a significant issue in areas experiencing rapid population change, or when the importance of a particular socio-demographic topic suddenly changes in response to new or emerging Government policies and priorities."[50]

46. Glen Watson, ONS, told us that it was not possible to expedite the publication of census data and that they had received representations that publishing raw data followed by a later, corrected, version caused confusion.[51] We were also told that the Government was not provided with early access to the data when it would be more up to date.[52]

47. We strongly consider that there is a need for more up to date information than the census provides. We urge the Office for National Statistics during their 'Beyond 2011' deliberations to ensure that whatever solution they propose provides greater access to current accurate data.


48. The normal working resource budget of the ONS has been around £140 million a year.[53] The running of the census, once every ten years requires the addition of thousands of staff and a budget of approximately £500 million. It is unlikely that the addition of such a task to any organisation would not interfere with the smooth running of the day-to-day tasks of that organisation. This is exacerbated by the high profile of the census operation.

49. One indicator of the impact is that census data takes so long to become available, the process occupies almost two years during which time those ONS employees are fully occupied on census work as opposed to the tasks they undertake eight years out of every ten. Glen Watson of the ONS outlined the timeline of the census:

    Census day was 27 March [2010], as everyone knows. The census field work finished in June, after we had spent a couple of months sending people out knocking on doors, reminding people of their obligations and chasing up non-responses. The capture and processing of all that information at our large processing facility in Manchester started at about the same time.


    We are now in the phase where we are doing further statistical processing of that data within the Office for National Statistics, and we are embarking on a process of quality assuring all the results.


    It is an incredibly complex process, and it will be next summer [2012] before we are in a position to get out the first set of results.[54]

50. We have some concerns that the operation of the census may unduly impact on the day to day operations of the ONS. We recommend that when considering how to provide constant, accurate data to Government, the ONS devise how this might be accomplished in a way that will be less intrusive to the operation of their day to day organisation.

20   Ev w19 Back

21   For example, Ev w38 Back

22   For example, Ev w22, para 5 Back

23   For example, Ev w15 Back

24   Ev w3 Back

25   Ev w16 Back

26   Ev w28 Back

27   Q 57 Back

28   Q 15 Back

29   Ev w37 Back

30   Ev w24 Back

31   For example, Ev w31 Back

32   Ev w31 Back

33   Ev 53 Back

34   Ev 42 Back

35   Ev w8 Back

36   Ev w37 Back

37   Ibid. Back

38   Ev w47 Back

39   Ev 55 Back

40   For example, Q 61 Back

41   For example, Q 53 Back

42   For example, Q 62 Back

43   Q 47 [Professor Allen] Back

44   Ev w38 Check Back

45   Ev 53 Back

46   Q 9 Back

47   Q 80 Back

48   Ibid. Back

49   Ref Back

50   Ev 49 Back

51   Q 90 [Glen Watson] Back

52   Q 114 [Jenny Dibden] Back

53   ONS website, 20 October 2010, Back

54   Q 89 Back

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© Parliamentary copyright 2012
Prepared 21 September 2012