Household projections for Scotland

Household projections for Scotland

Hugh MackenzieApril 2014

Summary

• What are the household projections?• How are they produced?

– Five inputs– Seven steps

• Variant projections

• How to get Census data & analysis

What are household projections?• Published every two years, 2012-based projections to be

published on 30 July 2014

• Cover a 25 year period

• Projections are produced by:– Council area (also SDP Areas and National Parks later

in the year)– Age of head of household– Household type (based on the number of adults and

children)

• The projections are designated as National Statistics by the UK Statistics Authority.

Input 1: Population Projections• Published every two years by NRS, 2012-based population

projections to be published on 14 May 2014

• Use the 2012 mid-year population estimates as a base

• For following years, this population is aged and estimates are made for:– Numbers surviving to the next year, using mortality rates– The expected number and age/sex structure of migrants– Number of births during the year, using fertility rates applied to the

number of women of childbearing age

• Variant projections are produced using different assumptions about fertility, life expectancy and migration.

Input 2: CE rates Proportion of the population that are resident in

communal establishments• By area, age group and gender• Data on CE residents is collected from a range of sources:

Establishment type Data source Year of dataCare Inspectorate (List of registered establishments) 2012ISD Care Home Census 2012Care Inspectorate (List of registered establishments) 2012SG Looked After Children Statistics 2012NRS Armed Forces Data Collection 2012DASA Regular Forces by Age and Sex 20122011 Census 2011ISD SMR01 (General/Acute) 2012ISD SMR04 (Mental Health) 2010ISD Continuing Care Census (Other NHS) 2012

Hotels, hostels and boarding houses 2011 Census 2011

Prisons SG Prison Statistics 2012SG Education Analytical Services 2012SG Directorate for Learning 2012

Student Halls of Residence - Further Education 2011 Census 2011

NRS Communal establishment address list 2011HESA 2011/12

Other 2011 Census 2011

Children's care

Adult care

Hospitals

Student Halls of Residence - Higher Education

Defence

Residential Schools

Step 1: Calculate private household population

Private household population = Total population x (1 - CE rate)• By area, age group and gender for each year• CE Rates are assumed to be constant

Project headship rates to 2035

Calculate private household

population to 2037 Calculate the

raw household projection

Constrain LA figures to

Scottish totals

Constrain to

household estimates

Minimum adult and child

adjustments

Sum LA figures to give final

Scottish figures

Final projections

Inpu

ts

Population projections

Communal establishment estimates

Headship rates

Household estimates

Household type distribution

Input 3: Headship ratesThe proportion of the private household population that

head a household

• Census data (1991, 2001 and 2011 censuses)• Head of household = first adult recorded on the census

form • By area, age group and household type

• “Non-headship” rates also included (the proportion that do not head any type of household)

• Every person is either the head of a household or a non-head, so for each area/age group the 7 headship rates and the non-headship rate sum to 1.

Comparison of different estimates of the distribution of household sizes in Scotland

0%

5%

10%

15%

20%

25%

30%

35%

40%

1 person 2 people 3+ people

Perc

enta

ge o

f all

hous

ehol

ds

Household size2011 Census2010-based Household projections - principal (2011)2010-based Household projections - alternative headship (2011)

Step 2: Project headship rates• When we only used two censuses, a modified two-point

exponential model was used.

• To make use of three censuses, two sets of projected headship rates are produced using the modified two-point exponential model. i. Using 1991 and 2001 censusesii. Using 2001 and 2011 censuses

• The two sets of projected headship rates need to be combined into a single set of headship rates.

Input 4: Household type distribution in 2012

• Data to come from the Scottish Household Survey (SHS).

• Annual survey, 2012 sample size of just under 11,000 households.

• We make an adjustment to the data based on differences found between the SHS and the Census in 2001 and 2011.

Step 2: Project headship rates (continued)

• Apply weights to the two sets of projected headship rates to combine them into a single set of rates.

• Weights chosen to minimise the difference between the survey data and the household projection.

• Allows up-to-date household type data to be included into the projections.

Step 3: Calculate raw household projectionNumber of heads of household =

Private household population * Headship rate • By area, age group and household type for each year • Number of heads of household = number of households





Constrain LA figures to

Scottish totals

Constrain to

household estimates


adjustments


Scottish figures

Final projections

Inpu

ts



Headship rates

Household estimates


Step 4: Control to Scottish totals• The sum of all LA projections are constrained to the

Scotland projection for each year• By age group and household type





Constrain council figures

to Scottish totals

Constrain to

household estimates


adjustments


Scottish figures

Final projections

Inpu

ts



Headship rates

Household estimates


Input 5: Household estimates

• Produced by NRS annually• Total number of households in each local

authority• Based on council tax data • More up to date household information than the

census data• Two years of data used (2012 and 2013)

Step 5: Constrain to household estimates• The sum of all projected households in each LA is

constrained to the household estimate for 2012 and 2013• 2014 onwards is adjusted by the same proportions as

2013






to Scottish totals

Constrain to

household estimates


adjustments


Scottish figures

Final projections

Inpu

ts



Headship rates

Household estimates


Step 6: Minimum adult and child adjustments

• The minimum number of adults required to fill all households in a council is calculated

• This is compared to the number of adults in the private household population in that council.

• In areas where the minimum number exceeds the private household population, the excess number of adults is calculated and the household types adjusted to reduce the number of adults needed. The adjustment is distributed across all multi-adult household types.

• Similar checks and adjustments are made for children if necessary.

Step 7: Calculate Scottish Totals• Final Scotland figures are calculated by adding together

all the local authority figures, so that the minimum adult/child adjustments are taken into account.






to Scottish totals

Constrain to

household estimates


adjustments

Sum council figures to give final Scottish

figures

Final projections

Inpu

ts



Headship rates

Household estimates


Variant projectionsTwo variant projections will be produced in addition to the principal projection:i. Low Migrationii. High Migration






to Scottish totals

Constrain to

household estimates


adjustments

Sum council figures to give final Scottish

figures

Final projections

Inpu

ts



Headship rates

Household estimates


Scotland’s CensusReleases 1 and 2 completedReleases 3A, 3B and 3C now published covering the bulk of Ethnicity, Identity, Language and Religion topics Release 3D to be published 15 May; tables from Population and Households topicsFurther releases dates confirmed shortlyQuick, easy (and FREE!) online access to all the data from www.scotlandscensus.gov.ukAll the standard output tables for all the available census geographiesData visualisations and maps online

http://www.scotlandscensus.org.uk/

Still to come…Remaining Release 3 tables – throughout year Origin-destination statisticsCensus microdata files (Samples of Anonymised Records)Alternative population statistics, eg workplace populationAnalytical reportsFurther details available in Outputs Prospectus on websiteActivity throughout 2014 to explore uses and benefits and what NRS can do to ensure you get the most out of the data

Finally – come to our Census Conference in Edinburgh on 25 June. Details on www.scotlandscensus.gov.uk

http://www.scotlandscensus.gov.uk/

Any questions?

For more info, contact:[email protected](0131) 314 4377www.nrscotland.gov.uk

2011 Census website: www.scotlandscensus.gov.ukFollow NRS on Twitter @NatRecordsScot

http://www.scotlandscensus.gov.uk/

Household projections for Scotland

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