Freedom of Information Request – reference
number F0003518
Dear
I am
writing in response to your request for information of 9th December
requesting further information on the figures provided on 28th
September regarding household and population growth in
I have
included a response to each of your points below.
1. ONS Population
Spreadsheet (see enc s.sheet - sheet no’s 1 +2).
As per the ONS spreadsheet from my previous FOI (enc),
Can you provide any comment / analysis evidence etc as to
whether the significant outflow of internal migration from Sheffield has an
impact on the level of internal migration into Barnsley, Rotherham, Doncaster
etc and what if any are the reasons/ assumptions behind the inflow of internal
migration to Rotherham, Doncaster, Barnsley etc. It would appear that
The Office for National Statistics has provided the following
figures which are internal migration outflows from
In addition to this, they have provided the 2006 based
Subnational Population Projections methodology guide which is attached and
details how internal migration is calculated.
Internal migration
outflows:
|
Origin |
Destination |
2006-2007 |
|
|
|
800 |
|
|
|
400 |
|
|
|
2000 |
2. Housing Numbers Template.
Can you please provide some comment on the following questions about the ONS spreadsheet headings on the Household Projections sheet that you have provided under the previous FOI.
Population – Is it the case that this primarily refers to the number of households that are being formed due to overseas migration and higher birth rates etc over the long term ?. Are there any other factors in this heading?. It would appear that overseas migration is the largest factor.
Some details of the method
used to produce the components of growth in the household projections are
contained within the report at:
http://www.communities.gov.uk/publications/housing/householdestimatesprojections
The components are
identified by holding all other factors in the model constant and allowing the
variable of interest to change and identifying the impact on the number of
projected households. This means that 585,000 households out of the total
growth in the region are due to the overall level of the population. Changes in
the level of the population can be brought about by births, deaths, international
net migration and internal net migration to a region. The spreadsheet on
projected population numbers show how each of these components contribute to
the change in the population in each area.
Age Structure – does this heading refer to the increase in the number of people living longer ie 83,000 Households are projected to arise due to the fact that there are more elderly people?.
The age structure
component to the household growth is based on a scenario where the population
level, marital status composition and household representative rates are held
constant. Therefore this reflects the impact of the changing age structure
(primarily more people living longer) on household numbers.
Marital Status- does this refer to the increase in the number of Households projected to form due to separation / divorce or are there any other factors?.
This reflects the marital
status projections produced by the ONS which can be found at http://www.statistics.gov.uk/STATBASE/Product.asp?vlnk=14491
which look at
trends in marriage, divorce and cohabitation by age and gender.
Household Representative Rates – does this heading refer to the fact that more people are predicted to remain single hence more single person households being formed etc.
A household representative
rate is the probability of anyone in a particular population group being part
of a separate household and can take any value between 0 and 1. The population
groups are defined according to sex, age (15 bands from 15-19 to 85 and over),
legal marital status and cohabitational status. This gives 240 population
groups and 240 representative rates in total.
Trends in household
representative rates are projected from the Census and Labour Force Survey.
Household representative rates can increase or decrease over time depending on
the sub-group of the population being considered. As the contribution of household
representative rates to household numbers in the region overall is positive and
as there is an increase in one person households then much of this will reflect
more one person households, but could also reflect fewer married couple or
multi-person households for example.
Remainder ?? – this figure shows a minus figure of -65,000. Can you explain what this figure is / relates to in terms of household projection factors ?
The
household projections model is non-linear and subject to top-down constraints.
The non-linearity in particular of the model means that there are non-additive
interactions between factors in the model. It is these interaction terms that
are being reflected in the -65,000.
3. Council House
Waiting Lists
(a)Can you please inform me / confirm if Council House waiting lists are, in any way, included in your model / projections for Y&H Households (ie 750,000 households) and if so could you give me an estimate of the figures for this category for the Authorities in the table attached (ie just the 750,000 figure only - no others ie ignore the 50% .or 75% estimates in sheets 3-6 of the attached spreadsheet
(b) If Council House waiting lists are not included in any way, why is this the case and how would this category be dealt with when assessing the number of homes to be built ?
The
household projections model is a demographic trend based model. Projected household representative rates are applied to a projection of the private
household population disaggregated by age, sex and marital/cohabitational
status and summing the resulting projections of household representatives.
The
key data sources and methodological stages are:
·
Population projections are taken from the latest (2006-based)
release by the Office for National Statistics (ONS) at the national and
subnational level, published in June 2008.
·
Marital status projections (de jure and de factor) at the national
level are taken from the latest release (2003-based). Projections at
subnational levels are assumed to follow the national pattern.
·
The institutional population is deducted from the total population
to give the private household population. The institutional population is
assumed to stay at a constant level for younger age groups and at a constant
share of the population for older age groups.
·
Household representative rates are extrapolated from Census data
(1971, 1981, 1991, 2001), disaggregated by age, sex and marital status. Labour Force Survey (LFS) data (from 2002 to
2007) are used to inform inter-Censual interpolations, post-Census estimates
and future trends of household representative rates. The LFS and Census data
are weighted together with the LFS data being given a lower weight than the
Census.
·
The resultant household representative rates are applied to the
projected private household population and summed across the age/sex/marital status
groups to give total household numbers.
·
Projections are initially undertaken independently at the national,
regional and sub-regional levels with regional projections then being
constrained to the national projections and sub-regional projections being
constrained to regional projections.
Therefore, council
house waiting lists are not used by the household projections. The
projections model is intended to give the long term demographic demand.
Regional
housing plans are set out through the planning process and regional strategies.
The Government’s policy on planning for housing is set out in PPS3 at
http://www.communities.gov.uk/planningandbuilding/planning/planningforhousing/
You’ll
see that this document requires plans to taken into account evidence of current
and future levels of need and demand for housing and affordability levels.
In the spreadsheet tabs 4
to 6 you asked for an estimate of the household / population numbers if the
levels of net international migration were reduced by 25%/ 50% /75% .
These analyses are not
available as neither CLG nor the ONS produce sub-national projections which show variants on the levels
of net international migration. National variant projections are produced which
can be found at
http://www.statistics.gov.uk/downloads/theme_population/NPP-2006/NPP06_NSOnline.pdf Table 15 for population variants.
And in the Statistics Release at
http://www.communities.gov.uk/publications/corporate/statistics/2031households0309
for households.
The ONS are undertaking
research into the feasibility of producing variants for the sub-national
population projections and hope to report on this later this year.
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about this letter, please contact me. Please remember to quote the reference
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Yours sincerely
Jane Hinton