Memorandum from Worcestershire County
Council
1. USES AND
DEFINITIONS
What are the uses of population estimates, and
how far do current population estimates meet the needs associated
with those uses? What are the effects of inaccuracies or inadequacies
in such estimates?
1.1 It is notable that small uncertainties
which are marginal in National terms for total population are
significant when applied in the context of different definitions
(eg age, nationality), geographies and categories. The importance
and the difficulties in capturing these "marginal uncertainties"
should not be underestimated.
1.2 Most particularly in recent years there
is the impact of the most uncertain and volatile aspect of population
estimation, migration. This is even more significant owing to
public perception due to the visibility of "non-british"
residents, and the impact of migrants demand on services being
identifiable (eg owing to language).
1.3 This has led (rightly) to an increased
concern for some authorities of perceived inaccuracies in population
estimation. Considerable work has been done by authorities individually,
collectively, and by ONS, to address the concerns. It should be
noted that, in our view, this has deflected effort from other
developments in ONS's programme of modernisation and systems development.
1.4 Of significance to us is the means of
establishing a consistent source for population estimates data.
Much of the information put forward in support of better population
estimates cannot, for various reasons, be used consistently across
the country (England, nor UK). We are satisfied that, within the
resource limitations they have, ONS are pursuing the need for
better data, it's proper analysis and use, with the right priorities.
They have consulted their users on their programmes in this regard.
How appropriate is a definition of the population
based on the usually resident population in the context of the
needs of the users?
1.5 The usually resident population definition
is one amongst many population definitions of potential use to
local authorities and the more complex living arrangements of
modern life mean that ONS must adapt to the changing situation.
At present students are allocated to their term time address for
100% of the time even though they spend part of their time at
their parents' address, while increasingly people have several
residences sometimes abroad. If you spend three days a week at
one residence and four with your family at another having one
simple view of usual residence is out dated. To this of course
must be added the much discussed topic of migrants and in particular
short term international migrants. Rather than just consider the
single issue of short term international migrants it is important
to consider all these issues together to reach a definition of
the usually resident population.
1.6 However we recognise the value in having
a single standard definition which can be consistently applied
across the country. Ideally, though, the population estimates
system would provide enough flexibility to allow authorities to
calculate populations against a range of definitions to better
inform service provision, provide a relevant base for performance
indicators and for policy development.
1.7 ONS preparatory work for the 2011 Census
has identified many ways of defining a person, in excess of 40,
23 alone for UK nationals, most of which are valid for some purpose.
In practice LAs use different definitions; a population count
could support these by providing different options.
1.8 The range of alternatives would ideally
include population present, day/night populations, term-time and
holiday populations, weekday and weekend populations. This of
course raises its own issue of the appropriate or incorrect use
of any particular definition for any particular use. However,
as mentioned below, the use of one definition does not prevent
the misuse of the data.
1.9 A major concern over population estimates
is their use (along with population projections) in resource planning
and allocation for Government departments, in particular, but
not solely, CLG. Bearing in mind also the time delay in preparing
population estimates, and still more, population projections,
our view is that a more responsive solution for the concerns that
LAs have in obtaining suitable resources could be to use other
sources of data, particularly service-based data, for short-term
resource planning. This would leave the estimates and projections
to provide an "underlying, long-term" basis for resource
decisions; these are typically reviewed for periods of 2-5+ years
(1-2 years following), with projections having terms of 25 years
and more.
1.10 This is a matter of the fitness for
use of (various) population counts.
1.11 Notwithstanding the need for accurate
population information, CLIP Population has identified areas where
the use of population data is inappropriate in the light of its
genesis, assumptions and robustness. Examples that we have identified
include the following.
1.12 Transport planning: A model used by
the Department for Transport (DfT), called TEMPRO (for Trip End
Model Presentation Program) has, in the past used as an input
the trend-based ONS projection of population to derive households
(an input to the model). This is increasingly being rectified
by the use of "policy-based" projections, obtained through
Regional Assemblies and (theoretically) aligned with Regional
Spatial Strategies. There are still issues over currency, spatial
disaggregation and the use of the modelling that are been addressed.
An area of particular concern is the lack of data on the changing
frequency of travel to work which has such a major impact on the
results of the model. Estimating the proportion of the population
who will travel four days or fewer to work each week is critical
when calculating distance travelled for sustainability purposes
or demand for travel.
1.13 NHS resource and CLG Financial Settlement
decisions use trend-based population projections that do not reflect
a "likely" scenario. This
1.14 All types of indicators increasingly
use rates to illustrate year-on-year (or shorter period) change.
In some cases these relate data from current administrative sources
to out-dated, and "not fit for purpose" data. This is
not to say the data are inaccurate, or the definitions unclear,
but they are unsuitable for the purpose they are put to. (eg BV
17 uses as denominator a population that includes people not in
work, when the numerator relates only to people in work.)
How does the quality and range of population statistics
in England and Wales compare with that available in Scotland,
Northern Ireland and internationally?
1.15 We would note that population-related
statistics in England and Wales compare very favourably with those
in the other home countries, with, as far as we are aware, two
exceptions. These are, in Scotland census and other data are not
subject to disclosure provisions, and that there are housing-based
data sources, derived from administrative data, that prove very
valuable to verify population data on a consistent basis.
1.16 While internationally there are official
population statistics that are considered more robust and accurate,
and command high levels of public trust, it is noteworthy that
these are almost exclusively based upon a population register
1.17 Thus, as the LGA submission states,
it is sensible to monitor how these things are done elsewhere.
ONS' intention to develop a business plan for an Integrated Population
Statistics system, which would presumably examine approaches taken
elsewhere, is therefore welcome.
1.18 We note that there is ambivalence amongst
local authorities on a register, but support for a more integrated,
administrative data based system as proposed with the ONS Proposals
for an Integrated Population Statistics System. This should deliver
more robust statistics, but could not guarantee widespread acceptance.
We also note that there is increasing public suspicion about collection
of data on the individual, so a register system would at least
have the advantage of being, in principal clear, transparent and
in the open. It is important that a separation is clear between
the administrative purposes of the register, and ONS's survey
role.
2. THE ROLE
OF THE
CENSUS
How does the Census contribute to the creation
of population statistics? Is the current frequency of Censuses
appropriate and, if not, how frequent should Censuses be?
What lessons have been learnt from the Test Census
carried out on 13 May 2007? What methods should be employed for
the distribution and completion of Census forms, including the
use of the Internet?
What steps should be taken to increase the rate
of responses to the Census, particularly in hard-to-reach areas?
How effective are plans to measure the extent of non-response
to the 2011 Census?
To what extent is there a trade-off between the
length of the Census form and its role in providing population
information? What questions should be included in the 2011 Census?
What forms should the outputs of the 2011 Census
take, how and when should they be made available and how should
they be integrated and coordinated with other information on population?
2.1 The importance of the Census in the
creation of population statistics cannot be over-estimated; it
is crucial. There are two aspects of the Census which need to
be recognised, first that it is a key method of collecting local
migration and travel to work data both of which have population
definition implications but most importantly it is the only way
that a complete understanding of the linkage between houses and
population can be achieved. With a significant proportion of the
population having several residences and vacant properties concentrated
in particular areas it is important that double counting of the
population does not take place. If issues such as gated communities,
absent households, short term migrants and persons abroad are
taken into account it is clear that we are dealing with a complex
situation which requires either a census or a register which can
identify if double counting is taking place. It is easy to criticise
the Census but there are even greater problems with the alternative
data sources.
2.2 The only feasible alternative to obtaining
even superficial information on the population (ie counts, age/sex,
personal, not relationship information) at district level or below
is a comprehensive, administrative register, and this would only
provide part of the census statistics. Having said this, in terms
of populations statistics, ie "simple counts", the currency
and accuracy of information between censuses becomes increasingly
important, such that currently, within 3 years of the release
of census information, the dynamics of population change are problematic.
2.3 We note that "hard-to-reach"
groups often correlate to the "hard to deliver services"
areas and rightly demand more attention, which is an approach
of ONS census planning. However, evidence that a non-geographic,
systematic deficiency in the census enumeration, applying to all
areas (for example the lack of response for certain aged males),
would require approaches that address being "hard-to-reach"
across the whole Census geography. In other words, "hard-to-reach"
areas are areas where certain "hard-to-reach" groups
are concentrated.
2.4 We would support the view that there
is significant value of having 4 Census pages per person rather
than 3. ONS have judged that response rates will not be affected,
and the only deterrent is financial cost. We understand that this
is the main difference between the 3 and 4 page versions. Less
information would be gathered, in particular on educational qualifications
and on industry/business of employer. These are both very important
in getting an understanding of disadvantage.
2.5 Output from the Census should be for
the usually resident population but more flexibility is required
to enable population counts on different bases to also be provided.
3. MID-YEAR
POPULATION ESTIMATES
How accurate and useful are the mid-year population
estimates for England and Wales, including information available
for local authorities and Strategic Health Authorities?
How appropriate is the methodology by which mid-year
population estimates are reached?
What are the most appropriate ways to ensure a
common level of accuracy in mid-year population estimates for
different areas and what steps should be taken to improve the
accuracy in areas where population is hard to measure?
3.1 The LGA submission generally covers
this point and earlier paragraphs of this submission.
3.2 With regard to the last question, the
revision of statistics creates difficulties for local authorities
because of the discontinuity and transition between significantly
different totals. Most noticeably in recent times, this occurred
following the 2001 Census, although this was not the first instance,
and more recent revisions of estimates and projections have repeated
the problem. A solution, but not one we would favour, is that
the population estimates are shifted by only limited amounts towards
the "new" totals.
3.3 This is an intractable difficulty when
thought of simply in terms of population estimates or statistics.
It is the effects of the revisions that should be the focus of
attention. We would particularly draw your attention to paragraph
1.8, with regard resource planning using consistent data across
local authorities.
4. THE ROLE
OF SURVEY
AND ADMINISTRATIVE
DATA
What role can and should be played by survey data
in the compilation of population statistics?
What role can and should be played by data from
General Practitioners and other health service data in the compilation
of population statistics?
What other data sources can and should be used
in the compilation of population statistics?
4.1 It should always be borne in mind that
the problems encountered by the Census, certainly when it comes
to coverage, are experienced to an even greater extent by survey
data. The particular strength of survey data relates to more complex
questions where the presence of an interviewer is critical.
4.2 Data taken from GPs registers provides
particular challenges. There are often issues relating to the
removal of patients from a list and this can lead to local biases.
For example some surnames particularly amongst the ethnic populations
are very common leading to difficulties in deleting records.
4.3 We note that the work of ONS to develop
an Integrated Population Statistics System would support many
of the points made in the LGA submission about the benefits of
administrative data. We also note, with reference to our earlier
comments about the "marginal" factors, and the LGA's
comments on "rare populations", that the collection
of data on the scale and movement of migrants, especially international
migrants, is the most critical element to be improved.
5. COOPERATION
WITH STAKEHOLDERS
How effectively has the Office for National Statistics
cooperated with stakeholders with an interest in and information
relating to population statistics and how can cooperation be improved
by the Statistics Board and by its Executive Office?
5.1 We would especially support the points
made in the LGA submission that ONS resources need to be taken
seriously if the concerns are to be addressed, we have seen the
effects of limitations in our work liaising with ONS, and have
on several occasions expressed concern about work streams having
to stop or be suspended.
5.2 We would also reinforce the point that
ONS needs cross departmental support in its efforts to improve
population statistics. It is an area where co-operation in and
thinking, planning and working will provide huge benefits. We
gave our support to this approach presented to us by ONSCD at
the last CLIP Population sub-group meeting.
December 2007
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