Plausibility Ranges for Population Estimates

Focusing on ranges for children

Outline

Aims

Data sources

Approaches

Results for children

Research on other age groups

Summary of benefits

Aim

Explore and

Combine

High estimate of population

Low estimate of population

Administrative sources

Data sources: Patient Register (0-15)

GP Patient Register

Usually resident population aged 0 to 15

Usual residents registered with a GP

Short term migrants

List inflation or registration lag for out-migrants

Multiple or duplicate NHS numbers

School boarders

Non-registration or registration lag for in-migrants

Erroneous list cleaning

• Adjusted to remove short-term migrants and duplicate records

Data sources: Child benefit (0-15)

Child Benefit

Usually resident

population aged 0 to 15

Usual residents registered for Child Benefit

Change of details lag for out-migrants

Children living abroad

Short term immigrants

Non-registration or registration lag

Change of details lag for in-migrants

School boarders

Clerical claims

• Adjustments to the child benefit data to compensate for coverage differences were not possible.

Data sources: Live births (age 0)

Live Births

Usually resident

population aged 0

Usual residents born in LA j

Immigration between birth and mid-year

In-migrants between birth and mid-year

Emigration between birth and mid-year

Out-migrants between birth and mid-year

Infant mortality

• The live births data has been adjusted for infant mortality (IMR).

• To allow for internal migration between birth and mid-year, the live births minus IMR has been re-distributed to local authorities using Child Benefit data.

Data sources: School Census (3-15)

School Census

Usually resident

population aged 3 to 15

Usual residents at a state maintained school

Short term immigrants

Change of details lag for out-migrants

Multiple pupil reference numbers

School boarders

Children aged 3and 4

Attendance lag for immigrants

Children at independent schools, pupil referral units or home educated

Change of details lag for in-migrants

• Although the School Census was available at individual record level, it was not possible to make any adjustments for over coverage.

Aggregate data: tolerance range approach

Mid-point (LA j)

Low source (LA j)

High source (LA j)

Step 1

Difference(LA j)

Patient Register = 3000

Mid-Point = 2800

Child Benefit = 2600

For example...

Difference= 400

Aggregate data: tolerance range approach

Range size (LA j) = 2 x Difference (LA j)

Difference (400)from Step 1

Range size(LA j = 800)

Step 2

Mid-point (LA j)

Low source

High source

2800

Upper limit (LA j) 3200

Lower limit (LA j) 2400

Aggregate data: tolerance range approach

10% of LAs10% of LAs

Step 3Percentage range size (LA j)

= Range size (LA j) / Mid-point(LA j)

min %

max %

• Range size (%) restricted to prevent very narrow or wide ranges.

rank of LAs

Record level data: linkage approach

Record-level sources (LA j)e.g. School Census e.g. Patient Register

Linked datasetunlinked School

Censusunlinked Patient

Register

Lower limit Upper limit

High linkage rate =Narrow range

for LA j

Summary of approaches

Age group Approach

Under 1s Combines Patient Register and Live Births adjusted with Child Benefit

1 to 4 year olds Combines Patient Register and Child Benefit

5 to 7 year olds8 to 11 year olds12 to 15 year olds

Lower limitLinked Patient register and school Census (England)

Upper limitCombines Patient register and Child Benefit

Source

Tolerance range

Tolerance range

Lower limit – linkage approach

Upper limit – Tolerance range

Results: data sources summary

Results: LA example - Adur (males)

0200400600800

10001200140016001800

estimated population of

under 1s

estimated population, age 1 to 4

estimated population age 5 to 7

estimated population age 8 to 11

estimated population

age 12 to 15

Adur, Males

Results: LA example - Adur (females)

0200400600800

10001200140016001800

estimated population of

under 1s

estimated population, age 1 to 4

estimated population age 5 to 7

estimated population age 8 to 11

estimated population

age 12 to 15

Adur, Females

Results: summary e.g. all LAs (males 8-11)

•Relatively few areas with estimates out of range

•Where areas have estimates out of range, often by small amount

•Rare for areas to have estimates more than 5% above upper limit or below lower limit

•Ranges quite narrow for ages 0 and 1-4, and more areas slightly out of range

Plausibility ranges for children

• Plausibility ranges are proof of concept at this

stage

• Project allowed us to demonstrate techniques

using aggregate and record level data

• Results published 27 March 2012 (report and

Excel-based tool)

• Results were discussed with LAs at roadshows

• Plan to further evaluate ranges in future

Research: 18-24 age group

• Age at which people most likely to migrate

• Sources: L2, HESA, Patient Register

• Where Patient Register is lower than population

estimates, these areas are predominantly

university towns

• Tested approach with HESA and PRDS linkage

• Further work on matching required

Research: 25-59/64 age group

• Investigated use of confidence intervals around

estimates Local Labour Market Database (L2)

• For quinary age groups sample size often small

• Difficulty with excluding short-term migrants from

latest tax-year data

• Not yet able to apply a universal method for all LAs

using the L2

Research: over retirement age group

• Patient Register and Work and Pensions

Longitudinal Study compared

• Data sources were often very close to each

other, potentially leading to ranges that were not

diagnostically useful

• Large differences between the sources for

females aged 60-64 and males aged 65-69

• Surprising result that population estimate higher

than PR and WPLS in 90+ age group

Summary of benefits

• Gathered together metadata and research on administrative sources in one report

• Knowledge of administrative sources fed back to teams quality assuring 2011 Census

• Helped inform future population estimates methods (e.g. school boarders)

• Evidence that small number of LAs may have had undercount of 0 & 1 year olds at 2001 Census

• Ranges may be used in quality assuring estimates in future