Impacts of international migration methodology improvements

1
Impacts of international migration methodology
improvements

• Jonathan Swan

2
Effects of New International Migration
Methodology by Methodological Change, 2002 to 2005
3
In-migration Estimates 2002 to 2005 London
4
In-migration Estimates 2002 to 2005 Yorkshire
and the Humber
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In-migration Estimates 2002 to 2005 East
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Comparison of Flag 4s vs Census
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Comparison of Existing Method and Flag 4s vs
Census
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Comparison of Improved Existing Method and Flag
4s vs Census
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Comparison of National Insurance Numbers (NINos)
vs Census
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Comparison of Improved Method and National
Insurance Numbers (NINos) vs Census
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Out-migration Impacts

• Impacts are very small at regional level
• Broadly speaking
• Student areas have increased out-migrants
• e.g. Cambridge
• Large urban areas have fewer out-migrants
• e.g. Manchester

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Switcher Assumptions

• Visitor Switchers
• Changes more or less even out at national level.
• Migrant Switchers
• Lower proportion of in-migrants who are switchers
• Higher proportion of out-migrants who are
  switchers
• Thus Migrant Switcher changes Increase total net-
  migrants
• But position can change from LA to LA
• And data used for assumptions will change over
  time

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LAs with highest net-migration increases2002 to
2005
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LAs with highest net-migration increases2002 to
2005
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Leeds an example of change, by cause

• In Migrants Improved Regional Method 11,800
• In Migrants Improved LA Method 1,900
• Visitor Switchers In Migrants 700
• Migrant Switcher Proportion In Migrants
  200
• Migrant Switcher Interaction In Migrants
  -600
• IN-MIGRANTS TOTAL 13,900
• Out Migrants Improved Method -5,100
• Visitor Switchers Out Migrants 300
• Migrant Switcher Proportion Out Migrants
  -200
• Migrant Switcher Interaction Out Migrants
  100
• OUT-MIGRANTS TOTAL -4,900
• NET-MIGRANTS TOTAL 18,800
• (Sign adjusted to show effect)

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LAs with biggest net-migration decreases2002 to
2005
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Bottom ten LAs with net-migration decreases2002
to 2005
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Westminster

• Rolled Forward Estimate 254,000
• Original Census Estimate 181,700
• Implied MYE over estimate of 72,500
• Estimate Following LA studies 203,200
• Implies MYE over estimate during
• the 1990s of 50,800
• Compare to revision for improved
• methodology (over four years) of -15,500

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In-migrants Change as percent of 2005 population
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In-migrants Change as percent of 2005 population
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Out-migrants Change as percent of 2005 population
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Out-migrants Change as percent of 2005 population
23
Net-migrants Change as percent of 2005
population
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Net-migrants Change as percent of 2005
population
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Subnational Population Projections

• Rich Pereira

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Overview of Strategy

• Revise 2004-based Subnational Population
  Projections (SNPPs) by
• Use revised 2004 MYE as a base
• Use revised 2002-2003 MYEs in 5 year reference
  period for setting future assumptions
• National assumptions and projected population
  remain the same

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What this means

• Revised 2005 and new 2006 estimates and migration
  will not be used in revisions
• The methodology improvement affects 2005 and 2006
  most for many areas. Since these are not used in
  2004-based projections, impact will be less
• Impact at LA level is therefore dependent on
  revised MYE back series only

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Impact on Subnational Projections

• Difficult to say at this stage how projected
  figures will change but they will be affected
• Change to absolute population levels
• Change to age/sex distributions affects future
  population levels
• Broadly, areas seeing a reduction in estimates
  for 2002-2004 will see a reduction in projections
  (though this will not always be the case
  especially where the change is small)

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Future Plans

• Revised 2004-based SNPPs to be published in
  September
• 2006-based National Projections to be published
  on October 23, 2007
• 2006-based SNPPs to be published in Summer 2008
• Will use 2006 MYE as base year
• Reference period for assumptions will be 2001-2006