Population Estimates and Projections in Hackney
Introduction
This briefing seeks to outline the key sources of population data available and provide
advice on their use, application and limitations. It includes comparative analysis on the
different sources of population data used by the Council and provides links to the
relevant websites and web pages containing further information on population data.
Population estimates and projections are crucial in ensuring the services that the
Council provide are aligned with the population as it stands presently and as it will be
in the future. However, the choice of different population statistics can often be
confusing: the size of Hackney’s population as of March 2011 varied between 237,646
up to 247,182 depending on the source used. There are two sources of population
data (both population projections and population estimates) used by the Corporate
Policy Team at Hackney: those produced by the Greater London Authority (“the GLA”)
and those produced by the Office for National Statistics (“the ONS”). Both sets use the
2011 census data as their primary source of information but their calculation
methodology and supplemental data sources differ, resulting in different estimates. In
addition to the official data sources, in 2008 and subsequently in 2011 Hackney
Council commissioned the Mayhew Study, an independent local population study, the
analysis of which is led by the Corporate Policy team. The main differences between
these data sources, together with details on which figures to use in defined projects,
are outlined below.
1. The Office of National Statistics (ONS)
The ONS produce two main population figures that are commonly used – the Mid-Year
Estimate and population projections for future years.
a) The Mid Year Estimates (“the MYE”)
The MYE are produced by ONS for all local authority areas across England and
Wales, and are ‘official’ estimates of population.
They estimate how many people live in the UK as a whole and in each local area
(rounded to the nearest 100), and provide a breakdown of the population by age and
gender together with information on components of change (e.g. births, deaths and
migrations). The estimates relate to the “usually resident” population i.e. population
estimates are estimates of people where they usually live.1
Geographically, data is available at the borough and ward level. Ethnicity statistics are
not part of the official ONS MYE and are therefore often produced with a time lag: the
most recent ONS ethnicity statistics were produced in 2009.
b) Sub-national Population Projections
The ONS also produce a second set of population data showing projections of
expected future populations for a twenty-five year period. They are aligned with the
MYE. These projections are based on past trends and illustrate changes to the
population of an area if trends continue in the same fashion. ONS assumptions about
future levels of fertility, mortality and migration are observed over a five-year reference
period. The sub-national population projections are revised every two years.
1
The usually resident population is defined by the standard United Nations definition for population
estimates, and includes people who reside in the area for a period of at least 12 months whatever their
nationality.
c) Limitations of MYE
There is much debate over the accuracy of the MYE particularly in the London
boroughs that have seen notable inward migration since 2001. Migration is constrained
to national assumptions about international and cross-border migration flows and
therefore doesn’t take account of the higher rates of population churn in the capital.
It is widely accepted that the MYEs in the past, between 2001 - 2010 significantly
undercounted the actual population found in most London boroughs: administrative
population counts (notably the 2011 Mayhew Population Study) have shown large
discrepancies. ONS is revising the back series of MYEs over the last decade to correct
previous inaccuracies, and in recent years the ONS have undertaken work to improve
migration statistics used in MYEs to avoid problems with migration statistics in MYEs
following the 2011 Census
d) Limitations of ONS projections
One of the main limitations of the ONS population projections is that they take no
account of planning policies or projected housing growth, and consequently take no
account of the capacity of different London boroughs to accommodate population
growth. There is therefore uncertaintly about their accuracy and for that reason they
are not recommended for use. GLA population projection figures (see below) are more
appropriate when considering population projections. Additionally, the ONS projections
use shorter term fertility data in construction of the projection model, and as a result
the projections are not as robust in estimating future numbers of children and young
people.
For the reasons stated above, the ONS MYE and population projections should not be
used in areas such as demand forecasting or service planning as doing so may lead to
an underestimation of service users and consequently may have a negative impact on
quality of service. Additionally, ONS statistics should be avoided when considering
infrastructure assessments as they do not take into consideration housing projections
or other relevant planning information.
e) When to use ONS Population Statistics and Estimates
Despite their limitations, the MYE remain the most widely used source for population
estimates and are the only directly comparable (across all local authorities in England
and Wales) source. It is these characteristics that explain their continuing use for
resource allocation, performance monitoring and central planning rather than their
actual accuracy.
The MYE provides detailed geographical information: data is available at borough and
ward level, and so can be used flexibly for detailed analysis.
The mid-year estimates are also used as the basis for calculating most of the
indicators that show rates and proportions. These are used wherever national
comparisons are required, and should be used as a basis upon which to calculate
other official statistics (such as the employment rate, fertility rate, birth rate etc) and as
a basis for comparative statistcial analysis’ and reports.
Office for National Statistics – Population estimation
Census of
population
10 yearly
Mid-year
population
estimates
Annual
Population
projections
Every two years
Current ONS Population Statistics:
ONS MYE for Hackney: 247,182 (published September 2012 and based on the 2011
Census.)
ONS Sub-national Population Projections for Local Authorities within London 2011 2031 (2011 based; published September 2012)
Further information:
ONS
MYE:
http://www.ons.gov.uk/ons/rel/pop-estimate/population-estimates-forengland-and-wales/mid-2011--2011-census-based-/stb---mid-2011-census-basedpopulation-estimates-for-england-and-wales.html
ONS SNPP: http://www.ons.gov.uk/ons/rel/snpp/sub-national-population-projections/Interim2011-based/index.html
2. The Greater London Authority
a) Population projections are issued annually by the GLA for all London Boroughs.
Current projections forecast up to 2031 and are available by age, gender and ethnicity
at both borough and ward level. Projections are based on births, deaths and migration
and utilising the ONS MYE and other Government data (from ONS and elsewhere).
Unlike the ONS population projections, the GLA projections do take into account the
impact future housing development is likely to have on an area and use the information
to estimate net migration. Due to the inclusion of housing estimates and projections
used in producing the GLA population projections, the statistics are always higher than
those produced by the ONS.
GLA data is available by gender, single year of age and aggregated ethnicity. By
geography data is available at the borough and ward level.
b) The GLA produce three population projection variants:
1. Constrained Population Projections (Estimates which are constrained and take
into account future housing growth - derived from the Strategic Housing Land
Availability Assessment – SHLAA – also known in Hackney as the Housing
Capacity Study);
2. Unconstrained population projections (Projections which do not take into
account the effect of future housing growth)
3. The Borough Preferred Projections (population projections which take into
account local estimates of future housing growth trends).
Each is built on a similar demographic basis, with different outcomes produced by
variant forecasts of housing capacity and growth.
c) Limitations
The GLA population projections are not recognised for use in performance or
monitoring so ONS statistics should be used in preference to GLA data when
submitting performance returns.
d) When to use GLA Population Projections
The demography team at the GLA are an excellent resource for London boroughs and
are better placed to understand the unique challenges that London boroughs face than
the ONS, which takes a national perspective on methodology. The data is produced
universally for all London boroughs so direct comparisons with neighbouring boroughs
are possible.
The Corporate Policy team regularly liaises with the GLA to ensure the accuracy of the
estimates that are produced. It is advised that generally the GLA “borough preferred”
projections are used over ONS or other GLA projections in service planning. The
Borough Preferred projections are recommended as these are based on our own
annually reviewed housing trajectories (produced by the Spatial Planning team).
The exception to this is in longer term planning where it is critical that demand is not
underestimated – in those cases the highest of the GLA figures (which is usually the
SHLAA) should be used.
All school roll projections in Hackney are sourced using “borough preferred”
projections as they are deemed the most accurate, taking account of specific planning
and housing documentation submitted to the GLA by the Council.
The GLA population projections will be updated in December 2012.
Current GLA statistics for Hackney:
GLA approximation of ONS mid 2011 population estimates and 2011 Censusbased short term sub national projection: 250,700 (2012 projection) 267,800
(2017 projection)
GLA population projections based on the 2011 census are due for release in
December 2012. Interim projections were released in July 2012 in order to inform
financial decision making across local authorities.
http://www.london.gov.uk/who-runs-london/mayor/publications/society/facts-andfigures/population
London Housing Capacity Study (LHCS)
http://www.london.gov.uk/shaping-london/london-plan/docs/strategic-housing-landstudy-09.pdf
For information regarding Hackney’s housing trajectories, please contact the spatial
planning team: spatialplanning@hackney.gov.uk
If you have any queries about GLA population projections, please contact
Helen.butler@hackney.gov.uk or Leila.lesan@hackney.gov.uk who are in regular contact with
the GLA and will endeavour to answer your query in the first instance or put you in touch with
the relevant contact at the GLA
3. Local Administrative Population Statistics (Mayhew)
a) The local administrative population study (“the Mayhew Study”) was first
commissioned by the Council in 2007 and has been commissioned again for 2011 and
is therefore the most up to date source of population data the Council possesses. The
population count consists of household and personal level data with characteristics
attributed to all Hackney residents. Data is collected on numerous variables including
(but not limited to) age, sex, ethnicity, housing tenure and benefit status. The ethnic
breakdown provides a far broader range of ethnicities than those in the census.
b) Limitations
The Mayhew Study is the minimum confirmed population count. Direct comparability
with other local authorities that haven’t undertaken comparable studies is not possible.
Comparisons with neighbouring boroughs that have undertaken Mayhew population
counts may be complicated to some extent by the different dates the counts were
undertaken. The Mayhew Study is not formally recognised nationally or regionally.
c) When to use the Mayhew Study
This is the best source to use for internal planning where a comparison to other
boroughs is not an issue. As well as providing an alternative population count, the data
within the Mayhew Study can also be manipulated and analysed to provide a broad
insight into the characteristics of Hackney households and residents, and can
therefore be used to meet specific service demands which are linked to target
populations. The database can be interrogated for various datasets and at various
geographies making it very versatile for planning targeted services.
Current Mayhew Population Statistics:
March 2011 Mayhew Study: 237,646
Follow this link to read the full Mayhew Population Report
Further Information
ONS
Methods:
http://www.statistics.gov.uk/about/data/methodology/specific/population/PEMethodology/
http://www.statistics.gov.uk/downloads/theme_population/short-methods-guide.doc
Communities and Local Government – housing projections:
http://www.communities.gov.uk/housing/housingresearch/housingstatistics/housingstat
isticsby/householdestimates/
Annexe 1: Summary of population data sources
SOURCE AND
DESCRIPTION
FREQUENCY LAST
PRODUCED
USES, PROS AND CONS
CENSUS / POPULATION ESTIMATES
Census of population
Every
Detailed small area data on the
ten years
2011
 Key benchmark for ONS population estimation.
 Informs decisions about public sector funding.
demographic and socio-economic
 Service planning (small area).
characteristics of the population.
 Pros: good for small area analyses and for
exploring detailed characteristics of population.
Cons: (can be) out of date.
ONS mid-year estimate (MYE)
Annual
2011 MYE
* ‘Official’ estimates of resident
released in
population for local authorities,
September 2012.
 Used for statistical returns to government & input
to calculation of some PIs.
 Population denominator for rates where
available by age and gender.
comparator data needed for other local
* Experimental MYE statistics also
authorities.
 Pros: useful for comparing Hackney with rest of
available by ethnicity and for small
areas.
England; ward level estimates.
 Cons: doesn’t take account of higher levels of
population churn in the capital; migration
information is based on estimates; controversy
over the accuracy of the estimates.
Mayhew – Local Population
N/A
March 2011
 Not just a population count: contains data on
Study
* Household and personal level
household and resident characteristics and can
data with characteristics attributed
and specific service demands.
therefore be used for internal service planning
 Pros: extremely versatile with broad information
to all Hackney residents.
on ethnicity.
* Hackney has commissioned two
 Cons: cannot be used for comparative analysis
studies: the first in 2007 and the
with other boroughs.
second in 2011.
POPULATION PROJECTIONS
ONS sub-national projections
Every two years
2011-based
(SNPP)
SNPP for years
* Official ONS projections, by age
2011-2031
 Used by CLG and other government departments
for funding allocation.
 Pros: none (from LA perspective).
 Cons: SNPP are trend based and no account is
and gender. From 2008 to 2033,
for all Local Authorities in England.
taken of expected housing development, so they
significantly understate likely population growth in
Hackney - not recommended.
GLA population projections
Annual
July 2012
* For London boroughs by age and
(at least)
Approximation
gender, to 2031.
Projections
 Used extensively by London boroughs for service
planning purposes.
 Used by GLA to underpin the London Plan.
* Data by ward, ethnic group,
 Only source of ethnic group projections.
labour force and household.
 Pros: good for comparing Hackney to other
* Takes account of development
data.
boroughs, and for ethnic profiling.
 Cons: not recognised for use in performance or
monitoring.
Annex 2:
Summary of population figures compared for Hackney
Source
ONS mid-year estimate (Census based)
Population
247,200
ONS sub-national projection (2012)
249,520
GLA interim projection (2012)
250,700
Mayhew local population study (2011)
237,646