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.
NATIONAL COVERAGE
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.
LONGITUDINAL STUDIES/THE ADVANTAGE
OF COMPARISONS OVER TIME
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.
RELIANCE ON OFFICIAL INFORMATION/DIFFICULTIES
OF COMBINING OTHER SOURCES
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]
CENSUS DATA AS REFERENCE POINT
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.
TIMELINESS
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.
THE IMPACT OF THE CENSUS ON THE
ONS
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, www.ons.gov.uk/ons/media-centre/statements/older-statements/spending-review-oct-2010/spending-review-2010-announcement.html Back
54
Q 89 Back
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