Mismatches and matches in address information from the Census and the BSO: A longitudinal perspective 2001-2011

Ian Shuttleworth and Brian Foley, Queen’s University Belfast

British Society for Population Studies annual conference

9th September 2015, University of Leeds

Presentation format

• Context

• Data source, research approach and methods

• Backdrop of societal change in Northern Ireland (NI) during the 2000s

• Research questions

• Results

• Summary and conclusions

Context

• Shift in approach to future production of UK population statistics

• Greater use of administrative data sources enhance quality of statistical outputs from 2021 Census

• Post-2021; move away from traditional census-taking approach

• Health service registration data - fundamental role important to improve understanding of data quality

research focus → accuracy of address information

Data source

• Northern Ireland Longitudinal Study (NILS) representative 28% sample (circa 500,000 individuals)

health card registration data from Business Services Organisation (BSO)

one of 104 designated birth dates

• Linked to census and vital events data

• Address information for NILS members updated through six-monthly data downloads provided by BSO

Research approach

• Assess quality of address information in NI health card registration data over time

• Cross-sectional comparison of address Super Output Area (SOA) from linked health card registration and census records

2001 Census

BSO health card registrations, April 2001

SOA of address

2011 Census

BSO health card registrations, April 2011

SOA of address

NILS NILS

Methods

• Descriptive statistics on rates of address match/mismatch in 2001 and 2011, based on all ages

• Multilevel logistic regression modellingbinary outcome variable (1 = SOA mismatch, 0 = SOA match)

hierarchical data (individuals nested within SOAs)

based on 16-74 age group with SOA recorded in both the health card registration and census data

circa 315,000 and 347,000 records for 2001 and 2011, respectively

Change in NI during the 2000s

Advances in information technology

Ageing population

Expansion of rental sector

Increase in migrant population

Demographic and socio-economic change

0

50

100

150

200

250

300

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80+

Es

tim

ate

(x

10

3)

Age group (years)

2011 2001

Population

Population by age band

1,500

1,550

1,600

1,650

1,700

1,750

1,800

1,850

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Es

tim

ate

(x

10

3)

Year ending mid-

Source: Northern Ireland Statistics and Research Agency (NISRA)

Demographic and socio-economic change

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Est

imat

e

Year ending mid-

Net migration

In-migration

Out-migration

0

10,000

20,000

30,000

40,000

50,000

Est

imat

e

2001 2011

Europe (excluding UK & Ire)

Other

Country of birth

Long-term migration

Source: NISRA

Demographic and socio-economic change

Housing tenure

0 10 20 30 40 50

Level 4 and above

Level 1 to 3

No qualifications

Percent

2011

2001

Education

0 10 20 30 40 50 60 70 80

Privaterented

Socialrented

Owneroccupied

Percent

2011

2001

Source: NISRA

Research questions

• How do the rates and geography of address mismatch in health card registration data in 2011 compare with the situation in 2001?

• What is the descriptive profile of address match/mismatch in 2011 and how does this compare with the situation in 2001?

• Has the association between address mismatch and relevant individual-, household- and area-level variables changed between 2001 and 2011?

• What is the transition in address match/mismatch status of NILS members between 2001 and 2011?

Address accuracy status

11.9%

85.9%

2.2%

14.5%

84.2%

1.3%2001 2011

n = 456,290 n = 485,185

Address match

Address mismatch

SOA missing in health card registration data

Source: NILS

Address mismatch rate, 2001

Belfast

Source: NILS

Address mismatch rate, 2011

Belfast

Source: NILS

Research questions• How do the geography and rates of address mismatch in health

card registration data in 2011 compare with the situation in 2001?

• What is the descriptive profile of address match/mismatch in 2011 and how does this compare with the situation in 2001?

• Has the association between address mismatch and relevant individual-, household- and area-level variables changed between 2001 and 2011?

• What is the transition in address match/mismatch status of NILS members between 2001 and 2011?

Address mismatch by age

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90+

Co

un

t

Age (years)

SOA match 2011

SOA match 2001

SOA mismatch 2011

SOA mismatch 2001

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90+

Per

cen

tAge (years)

SOA match 2011

SOA match 2001

SOA mismatch 2011

SOA mismatch 2001

Source: NILS

2001 2011

Sex

Marital status

Address match

Address mismatch

SOA missing in health card registration data

88%

84%

10%

13%

Female

Male

86%

82%

13%

16%

Female

Male

90%

88%

84%

82%

78%

7%

10%

14%

16%

20%

Widowed

Married

Single

Divorced

Separated

91%

86%

85%

82%

81%

8%

12%

14%

17%

18%

Widowed

Married

Divorced

Single

Separated

0% 50% 100%

0% 50% 100% Source: NILS

2001 2011

Limiting long-term illness

Education

Address match

Address mismatch

SOA missing in health card registration data

88%

84%

80%

9%

14%

18%

Noqualifications

Level 1 to 3

Level 4 andabove

89%

85%

9%

12%

Yes

No

0% 50% 100%

0% 50% 100%

86%

84%

12%

15%

Yes

No

88%

82%

81%

11%

17%

17%

Noqualifications

Level 1 to 3

Level 4 andabove

Source: NILS

2001 2011

Country of birth

Address one year ago

Address match

Address mismatch

SOA missing in health card registration data

86%

78%

12%

17%

UK/Ireland

Non-UK/Ireland

85%

76%

14%

20%

UK/Ireland

Non-UK/Ireland

89%

61%

54%

9%

23%

43%

No addresschange

Moved fromoutside UK

Moved fromwithin UK

86%

73%

54%

13%

20%

45%

No addresschange

Moved fromoutside NI

Moved fromwithin NI

0% 50% 100%

0% 50% 100%

Source: NILS

2001 2011

Tenure

Accommodation type

Address match

Address mismatch

SOA missing in health card registration data

88%

87%

69%

10%

12%

27%

Owneroccupied

Social rented

Privaterented

86%

85%

73%

13%

14%

25%

Owneroccupied

Social rented

Privaterented

87%

87%

74%

72%

64%

10%

12%

19%

25%

31%

Detached

Semi-D/Terraced

Caravan/Mobile

Flat/Apartment

Communal

86%

84%

77%

73%

63%

13%

15%

20%

25%

35%

Detached

Semi-D/Terraced

Caravan/Mobile

Flat/Apartment

Communal

0% 50% 100%

0% 50% 100% Source: NILS

Research questions

• How do the geography and rates of address mismatch in health card registration data in 2011 compare with the situation in 2001?

• What is the descriptive profile of address match/mismatch in 2011 and how does this compare with the situation in 2001?

• Has the association between address mismatch and relevant individual-, household- and area-level variables changed between 2001 and 2011?

• What is the transition in address match/mismatch status of NILS members between 2001 and 2011?

Sex (ref cat: Male) FemaleAge (ref cat: 16-24 yrs) 25-34 yrs

35-44 yrs

45-54 yrs

55-64 yrs

65-74 yrsMarital status (ref cat: Single) Married

Separated

Divorced

WidowedLimiting long-term illness (ref cat: Yes) NoQualifications (ref cat: No) YesReligion (ref cat: Catholic)Protestant & other Christian

Other religionsCountry of birth (ref cat: UK/Ireland) Non-UK/IrelandNSSEC (ref cat: Professional)Intermediate

Routine

StudentAddress one year ago (ref cat: No move) Moved from within UK

Moved from outside UKTenure (ref cat: Owner occupied) Social rented

Private rented

Communal2001 Population density, Log10 scale Quartile 2(ref cat: Quartile 1) Quartile 3

Quartile 42005 Deprivation Score, Log10 scale Quartile 2(ref cat: Quartile1) Quartile 3

Quartile 4

Between-SOA variance: null model 0.21, specified model 0.14315,204 Level 1 units, 890 Level 2 units

Lower odds Higher odds

-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

Odds ratio

Binary logistic multilevel model: 2001

Source: NILS

Sex (ref cat: Male) FemaleAge (ref cat: 16-24 yrs) 25-34 yrs

35-44 yrs

45-54 yrs

55-64 yrs

65-74 yrsMarital status (ref cat: Single) Married

Separated

Divorced

WidowedLimiting long-term illness (ref cat: Yes) NoQualifications (ref cat: No) YesReligion (ref cat: Catholic)Protestant & other Christian

Other religionsCountry of birth (ref cat: UK/Ireland) Non-UK/IrelandNSSEC (ref cat: Professional)Intermediate

Routine

StudentAddress one year ago (ref cat: No move) Moved from within NI

Moved from outside NISOA (mis)match status 2001 (ref cat: Matching) Mismatched

SOA missing in BSO dataTenure (ref cat: Owner occupied) Social rented

Private rented

Communal2011 Population density, log scale Quartile 2(ref cat: Quartile 1) Quartile 3

Quartile 42010 Deprivation Score, log scale Quartile 2(ref cat: Quartile 1) Quartile 3

Quartile 4

Between-SOA variance: null model 0.12, specified model 0.05347,617 Level 1 units, 890 Level 2 units

Lower odds Higher oddsBinary logistic multilevel model: 2011

-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

Odds ratio Source: NILS

Research questions

• How do the geography and rates of address mismatch in health card registration data in 2011 compare with the situation in 2001?

• What is the descriptive profile of address match/mismatch in 2011 and how does this compare with the situation in 2001?

• Has the association between address mismatch and relevant individual-, household- and area-level variables changed between 2001 and 2011?

• What is the transition in address match/mismatch status of NILS members between 2001 and 2011?

Transition in address match/mismatch status

279,899 40,287 890 321,076

87.2% 12.5% 0.3% 100.0%

75.2% 10.8% 0.2% 86.3%

30,612 12,284 207 43,103

71.0% 28.5% 0.5% 100.0%

8.2% 3.3% 0.1% 11.6%

4,817 763 2,239 7,819

61.6% 9.8% 28.6% 100.0%1.3% 0.2% 0.6% 2.1%

SOA mismatchSOA missing in health card regisration data

2011

Total

SOA match

SOA match

SOA mismatch

SOA missing in health card regisration data

2001

n = 371,998

Source: NILS

Summary of main findings

• Increase of circa 2% in the address mismatch rate in 2011

• Highest rates of address mismatch in urban areas in both years

• Descriptive profile of address match/mismatch very similar in 2011

compared to 2001

• High odds of address mismatch in 2011:male25 to 34 age groupmoved in the year before the censusaddress mismatch in 2001private rentersmore densely populated areas

Conclusions

• Despite demographic and socio-economic change in NI, address mismatch situation in 2011 similar to that in 2001

• Conservative estimate of address mismatch

• Implications for sub-national population estimates and other statistics they underlie, e.g. health and economic indicators

• Increasingly mobile population → difficult to reference individuals to a single address

Future analysis

• Further analysis of NILS members exhibiting address mismatch in both 2001 and 2011

• Use subsequent downloads of BSO data after April 2011 to investigate the lag in updating of address information in health card registration data to match that recorded in the 2011 Census

• Undertake the analysis using Unique Property Reference Number, which will provide an insight into mismatch at the individual address level

The help provided by the staff of the Northern Ireland Longitudinal Study and the NILS Research Support Unit is acknowledged. The NILS is funded by the Health and Social Care Research and Development Division of the Public Health Agency (HSC R&D Division) and NISRA. The NILS-RSU is funded by the ESRC and the Northern Ireland Government. The authors alone are responsible for the interpretation of the data and any views or opinions presented are solely those of the author and do not necessarily represent those of NISRA/NILS. 

NILS-RSU Contact Details:

Email: nils-rsu@qub.ac.uk

Acknowledgement

0

50

100

150

200

250

300

350

400

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72

Co

un

t

Age (years)

2011 age

2001 age0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8+

Per

cen

t

Number of address changes recorded in BSO data between 2001 and 2011

Matched address in both 2001 and 2011

Mismatched address in both 2001 and 2011

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

Male Female

Co

un

tSex

Characteristics of NILS members with address mismatch in both 2001 and 2011