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A model-based approach for estimating international emigration for local a uthorities. Brian Foley, Office for National Statistics BSPS d ay meeting London School of Economics 16 th May 2013. Presentation format. Background information - PowerPoint PPT Presentation
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A model-based approach for estimating international emigration forlocal authorities
Brian Foley, Office for National Statistics
BSPS day meetingLondon School of Economics
16th May 2013
Presentation format
• Background information- importance of accurate international migration
estimates• Issues with estimating emigration from local
authorities (LAs)• ONS emigration model
- overview- updating of the model for the year ending mid-
2012 emigration estimates • Future work
Need for accurate international migration estimates at local authority level
• International migration is a key component of population change
• Accurate estimation of migration flows necessary for LA mid-year population estimates
Definition
• ONS use the United Nations recommended definition of an international long-term migrant:- a person who moves to a country other than that
of his or her usual residence for a period of at least a year (12 months), so that the country of destination effectively becomes his or her new country of usual residence
Estimating international migration at local authority level
• Migration Statistics Improvement Programme• Administrative data to distribute immigration
totals from International Passenger Survey (IPS) - National Insurance number- Higher Education Statistics Agency- Flag 4s from the GP Patient Register
• What about emigration ??
Emigration at local authority level – difficult to estimate
• No administrative or survey data sources exist that provide information on long-term emigration from LAs
• Small sample size of emigrants in the IPS
International Passenger Survey, 2002 to 2011
Source - http://www.ons.gov.uk/ons/rel/migration1/long-term-international-migration/2011/1-02-ips-margins-of-error--1975-2011.xls
IPS estimates of emigration at national (2002-2011) and regional level (2011)
Source - http://www.ons.gov.uk/ons/rel/migration1/long-term-international-migration/2011/1-02-ips-margins-of-error--1975-2011.xls
Emigration estimates for the different levels of geography
IPS direct estimate
IPS direct estimate
Distribute using IPS 3 year average
Distribute using regression model
National
Regional
Intermediate(NMGo)
Local authority
Estimating emigration at local authority level
• ONS employs a Poisson regression model• Produces estimates of international
emigration at LA level (where IPS data are insufficient) by borrowing strength from other data sources- Census- Survey- Administrative
Overview of the emigration model
• Fitted model based on relationship between number of emigrants leaving an LA (IPS-based) and a number of LA-level socio-economic and demographic variables (covariates)
• Strengths of model:- availability of data for all LAs- more robust estimates
Consideration of covariate data
• Variety of factors associated with why emigrants would leave an area
• Data that capture both a person’s desire and ability to emigrate
Relationship between international long-term emigration and socio-demographic variables at local authority level in England and Wales, year ending mid-2011
Stepwise model
IPS estimate of LA emigration
(3 year average)
Covariate 1
Covariate 2
Covariate i
Covariate 3
Covariate 1
Multicollinearity testing
Covariates selected by stepwise model in more than one year
LA level data
Emigration model specification
Covariate i
Final modelLA emigration estimates constrained to sum to the relevant NMGo estimate
Fitting the final model
• Geographic indicators included• Model fitted for each year ending mid-2002 to
mid-2006 • Fixed set of model covariates used
- improves quality of time series• General patterns can be observed
- relationship between covariates and IPS emigration estimates
Original emigration model (finalised 2010)
LA emigration estimates
Number of retired people (-)
Number of lone and working parents (-)
Number of students in Higher/Further education (+)
Number of people of Western Europe country of birth (+)
Number of people of Oceania country of birth (+)
Number of people of North American country of birth (+)
Number of household spaces in terraced housing (+)
Number of household spaces in shared housing (+)
Number of hostels (+)
Number of people of Indian ethnicity (-)
Number of internal in-migrants (-)
Number of international in-migrants (+)
Annual Population Survey
2001 Census
Population Statistics Division, ONS
Updating the model for the year ending mid-2012 emigration estimates
• Rationale- availability of 2011 Census data- availability of administrative data- appropriate to re-examine the underlying relationships
in the model over a more recent time-period- change in dynamics of international migration to/from
UK since the mid-2000s
Covariate data sources employed
• 2011 Census data- country of birth, ethnicity, housing status
• Administrative data available to ONS- Higher Education Statistics Agency (HESA)- Migrant Worker Scan
• Annual Population Survey- economic activity data
• Home Office - crime statistics
Stepwise model
IPS estimate of LA emigration
(3 year average)
Covariate 1
Covariate 2
Covariate i
Covariate 3
Covariate 1
Multicollinearity testing
Covariates selected by stepwise model in more than one year
LA level data
Emigration model specification
Covariate i
Final modelLA emigration estimates constrained to sum to the relevant NMGo estimate
Updated model for year ending mid-2012 emigration estimates at LA level
Number of hostels (+)
Number of people of Oceania country of birth (+)
Number of people of African country of birth (+)
Number of people aged 16+ in employment (-)
Number of people of North American country of birth (+)
Number of in-migrants of EU8 nationality (+)
LA emigration estimates
Annual Population Survey
2011 Census
Migrant Worker Scan
• Range from ca. 20 to 8,000
• Higher emigration flows associated with London and the larger regional cities
<250250-499500-749750-9991,000-1,9992,000-3,9994,000-6,999>7,000
Modelled estimates of emigration from local authorities in England and Wales, year ending mid-2011
Modelled emigration estimates
• Range from ca. 0.2% to 6.0%
• Modelled emigration estimates less than 2% of the LA population in 340 of the 348 LAs in England and Wales
<0.200.20-0.340.35-0.490.50-0.740.75-0.991.00-1.491.50-2.49>2.50
Modelled estimates of emigration as a percentage of local authority population, year ending mid-2011
Emigration as % of LA population
Future work
• Ongoing research into developing an improved modelling approach for producing emigration estimates at LA level- identify additional covariates, other data sources- capture forthcoming changes in international
migration patterns to/from UK- reassess how geographic effects are captured and
accounted for
Thank you for your attention
Any questions ?