local population projection in practice - david cullum

Local Population Projection in practice

David CULLUMDeputy Manager

Research TeamNovember 2009

•Why did we do our own local projection?•How did we do it?•What did our local projection tell us?•What are we doing with our local projection?

Why did we do our own local projection?

ONS a top-down ‘disaggregation’ of national projections

ONS based on past 5 years trend – which were anomalous for Gloucestershire

Significant differential between ONS MYE and our own local estimates

Why did we do our own local projection?

ONS based on past 5 years trend – which were anomalous for Gloucestershire

•Historically high levels of housebuilding•Significant influx of A8 migrant workers•Also, 5-year ‘trend-based’ projections are ‘policy-blind’

Why did we do our own local projection?Significant differential between ONS MYE and our own local estimates

•ONS say 582,600 for mid 2007•We reckon 594,700•Based on GP registrations/electoral registers

How did we do it?We used POPGROUP© with

•Local population base•Local fertility rates•Local mortality rates•Local migration estimates•Residential development plans (RSS)

How did we do it?Local population base•12,000 higher than ONS MYE at mid 2007

-500

0

500

1,000

More in GCC

More in ONS

Very young Very old

How did we do it?Local fertility & mortality rates

•Locally observed fertility and mortality rates•Provided by Glo’shire NHS•Future vital trends modelled using GAD estimated rates

How did we do it?Local migration estimates

Used ONS District inflow/outflow data to derive rates for internal (within UK) migration

International Migration based on:•NINO•Migrant Worker study for length of stay•High levels of A8 in-migration in short term, ‘decaying’ to EU norm for Glo’shire after 10 years

How did we do it?Residential development plans (RSS)

•Draft Regional Spatial Strategy housing targets for Districts•51,000 houses in County 2008-2026•Annual targets for each district input into projection model•Significant policy influence

What did our local projection tell us?

540,000

560,000

580,000

600,000

620,000

640,000

660,000

680,000

2007 2012 2017 2022

Local Projection

ONS projection

What did our local projection tell us?

Local growth rate 8.8%ONS rate 13.7%

What did our local projection tell us?

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

0-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85plus

our projection

ONS 2006 based

Projected population 2026

What did our local projection tell us?

ONS projecting a more elderly population

More people of parenting age in our local projection

What did our local projection tell us?

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

0-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85plus

our projection

ONS 2006 based

Projected population 2026

What are we doing with our local projection?

What are we doing with our local projection?

What are we doing with our local projection?

80

85

90

95

100

105

110

115

120

125

130

2007 2012 2017 2022

2007=100

Young Offender projections 2007 to 2026

CheltenhamCotswoldForest of DeanGloucesterStroudTewkesbury