Life expectancy by NS-SEC Structure, technical and conceptual issues and resultsBSPS 8 Sept 2011

Brian JohnsonONS Health & Life Events DivisionNewportBrian.johnson@ons.gsi.gov.uk

Introduction

• Why life expectancy by NS-SEC?• What is NS-SEC and how is it derived?• Why is the ONS Longitudinal Study vital to

this analysis?• Main technical problems and approach to

them• Conceptual concerns • Summary results

Background

• ONS has produced life expectancy by Registrar General’s social class (RGSC) for the period 1972-2005

• In 2001 RGSC was replaced by NS-SEC for official statistics

• Need to produce life expectancy by NS-SEC• This is how it was done

Registrar General’s social class

Non-manual

I Professional

II Managerial and technical

IIIN Non-manual skilled

Manual

IIIM Manual skilled

IV Manual semi-skilled

V Manual unskilled

Life expectancy at birth by social class, for male & females, England and Wales, 1972-2005. Non-manual vs Manual

65

70

75

80

1972-76 1977-81 1982-86 1987-91 1992-96 1997-2001 2002-2005

Years

Non-manual

Manual

70

75

80

85

1972-76 1977-81 1982-86 1987-91 1992-96 1997-2001 2002-2005

Years

Non-manual

Manual

Source: ONS Longitudinal study

Males Females

What is NS-SEC?

• Socio-economic classification based on occupation

• Conceptually based on ‘employment relations’

• Job security/prospects/autonomy• ‘service contract’ relationship• ‘labour contract’ relationship

NS-SEC operational and analytical categories

Operational categoriesSeven-class Five-class Three-class

L1 1 Employers in large establishments

L2 2 Higher managerial occupationsL3 3-6 Higher professional occupations

L4 7-10 Lower professional and higher technical occupations

L5 11 Lower managerial occupations

L6 12 Higher supervisory occupationsL7 13-16 Intermediate occupations 3 Intermediate

occupations2 Intermediate occupations

L8 17-18 Employers in small establishmentsL9 19-20 Own account workersL10 21 Lower supervisory occupationsL11 22-23 Lower technical occupationsL12 24-30 Semi-routine occupations 6 Semi-routine

occupationsL13 31-35 Routine occupations 7 Routine occupations

5 Semi-routine and routine occupations

1 Professional and managerial occupations

2 Intermediate occupations

3 Routine and manual occupations

4 Small employers and own account workers5 Lower supervisory and technical

3 Small employers and own account 4 Lower supervisory and technical

1 Professional and managerial occupations

1 Higher managerial and professional occupations

2 Lower managerial and professional occupations

Source: Rose D and Pevalin D (ed) (2003) A Researcher’s Guide to the National Statistics Socio-economic Classification.

Part of NS-SEC derivation matrix

1.1 Employers in large organisations and higher managers

1.2 Higher professional occupations

4 Self-employed and own account workers

2 Lower managerial and professional occupations

Source: ONS (2002): The NS-SEC User Manual

Standard Occupational Classification 2000 Empl-oyer

Self-employed

manager

super-visor

emp-loyee

1111 Senior officials in national gov't 1.1 1.1 1.1 1.1 1.11112 Directors of major organisations 1.1 1.1 1.1 1.1 1.11113 Senior officials in local gov't 4 4 1.1 1.1 1.11114 Senior officials of other organisations 4 4 2 2 21121 Production and works managers 4 4 1.1 1.1 1.11122 Managers in construction 4 4 2 2 21123 Managers in mining and energy 4 4 1.1 1.1 1.11131 Financial managers & chartered secs 1.2 1.2 1.1 1.1 1.11132 Marketing and sales managers 4 4 1.1 1.1 1.1

Life Table (illustrative)

x n a x pop death M x q x p x l x d x L x T x e x

<1 0 1 0.1 2,533 20 0.007896 0.0078401 0.992160 100000 784 99294 7198691 71.991-4 1 4 0.5 11,130 1 0.000090 0.0003593 0.999641 99216 36 396793 7099397 71.555-9 5 5 0.5 15,519 2 0.000129 0.0006442 0.999356 99180 64 495742 6702604 67.58

10-14 10 5 0.5 16,409 4 0.000244 0.0012181 0.998782 99116 121 495280 6206862 62.6215-19 15 5 0.5 16,133 9 0.000558 0.0027854 0.997215 98996 276 494289 5711582 57.7020-24 20 5 0.5 21,482 10 0.000466 0.0023248 0.997675 98720 230 493026 5217293 52.8525-29 25 5 0.5 15,997 22 0.001375 0.0068527 0.993147 98490 675 490765 4724267 47.9730-34 30 5 0.5 16,026 35 0.002184 0.0108605 0.989140 97816 1062 486422 4233501 43.2835-39 35 5 0.5 19,800 34 0.001717 0.0085492 0.991451 96753 827 481698 3747080 38.7340-44 40 5 0.5 16,076 39 0.002426 0.0120568 0.987943 95926 1157 476739 3265381 34.0445-49 45 5 0.5 13,404 59 0.004402 0.0217688 0.978231 94770 2063 468690 2788642 29.4350-54 50 5 0.5 13,027 108 0.008290 0.0406107 0.959389 92706 3765 454120 2319953 25.0255-59 55 5 0.5 10,051 136 0.013531 0.0654412 0.934559 88942 5820 430157 1865832 20.9860-64 60 5 0.5 10,220 176 0.017221 0.0825516 0.917448 83121 6862 398451 1435675 17.2765-69 65 5 0.5 9,190 320 0.034820 0.1601602 0.839840 76259 12214 350763 1037224 13.6070-74 70 5 0.5 7,427 445 0.059917 0.2605539 0.739446 64046 16687 278510 686461 10.7275-79 75 5 0.5 5,231 414 0.079144 0.3303543 0.669646 47358 15645 197679 407951 8.6180-85 80 5 0.5 2,884 355 0.123093 0.4706350 0.529365 31713 14925 121253 210272 6.6385+ 85 11 0.5 1,840 347 0.188587 1.0000000 0.000000 16788 16788 89019 89019 5.30

Period and Cohort Life expectancy

• Period life expectancy (shown here) reflects mortality rates prevailing at all ages during calendar period to which it refers

• Therefore ‘life expectancy at birth’ for child born in 2004 is the number of years that child could expect to live if age-specific mortality rates stayed as in 2004

• Cohort life expectancy allows for anticipated future changes in mortality rates – projection implies element of subjectivity

LS Structure

1971

Original sample: 530,000

members; selected from 1971 Census

1971

Original sample: 530,000

members; selected from 1971 Census

1981

534,000 sample

members found at 1981

Census

1981

534,000 sample

members found at 1981

Census

1991

543,000 sample

members found at 1991

Census

1991

543,000 sample

members found at 1991

Census

2001

540,000sample

members found at 2001

Census

2001

540,000sample

members found at 2001

Census

Entries 1971-2008New Births 272,000Immigrations 174,000

Entries 1971-2008New Births 272,000Immigrations 174,000

Exits 1971-2008Deaths 239,000Embarkations 40,000

Exits 1971-2008Deaths 239,000Embarkations 40,000

Events: 1971-2008Births to sample women 260,000Births to sample men 49,500Infant Deaths 2,200Widow(er)hoods 82,000Cancer registrations 114,000

What can the LS offer the study of life expectancy by social classification?

• Based on census returns and administrative sources – low levels of ‘attrition’ (compared with survey data)

• Can attribute social indicator (eg. social class/occupation) several years before death – no need to rely on death registration

• Eliminates numerator-denominator bias - uses actual person-years at risk as denominator

Hierarchy for assignment of socio- economic classPresent at a census 81-01

Present 81ownspouse'sfather'smother's

Present 91ownspouse'sfather'smother's father's at birth 1981-91, mother's at birth 1981-91

Present 01ownspouse'sfather'smother's father's at birth post 1991-2001, mother's at birth 1991-2001

Not present at a censusfather's at birthmother's at birth

Person-years at risk

AGECalendar 60 61 62 63 64Year Census 1971

1971 5 B/////////////// 3

1972 9 B/////////////// 3

Year Age PYRs1973 9 B group

/////////////// 3 1971 60 5 months4 61 3 months

1974 D 1972 61 9 months62 3 months

1973 62 9 months63 3 months

Period at risk in younger age-group in each calendar year 1974 63 4 months/////////////// Period at risk in older age-group in each calendar year

Source: Fox AJ & Goldblatt PO Series LS No 1 OPCS

Members’Occupation/emp

status at census81,91,01

Non-members’Occupation/emp

status at census81,91,01

New births80’s,90’s,00’s

Father/mother Occ/emp status

NS-SEC Classifica-tionprogram

Deaths & Pyrs

program

Age-specific mortality rates

LifeTables

NS-

SEC

DERIVATION

MATRICES

819101

CancelledCiphers

Structure of Life Expectancy by NS-SEC project

OwnNS-SEC

Father’sMother’sSpouse’sNS-SEC

Father’sMother’sNS-SEC At birth

NS-SEC80Derivation

Matrix project

Losses toFollow up

Components of the project

1. Construct “NS-SEC80” derivation matrix using 1981 occupational classification and employment status to produce (reduced) NS-SEC classification for 1981 Census

2. Construct ‘own’ NS-SEC at each census where present3. Construct father’s, mother’s and spouse’s NS-SEC at 1981,

1991 & 2001 censuses where present, using LS non-members file

4. Construct father’s and mother’s NS-SEC for 1980’s, 1990,s and 2000’s new births

5. Construct hierarchical scheme for assigning ‘sec’ to each LS member, using own or father’s, mother’s, or spouse’s class

6. Adapt rule-based programs to obtain age-specific mortality rates by NS-SEC

NS-SEC90 analytic classes– using SOC90

soc90 STANDARD OCCUPATIONAL CLASSIFICATION 1990 OCCUPATION UNIT GROUP TITLEEmp- Self-emp Manager Super Employee

loyer no visoremployees

100 General administrators; national government 1.1 1.1 1.1 1.1 1.1

101 General managers; large companies and organisations1.1 1.1 1.1 1.1 1.1

102 Local government officers 4 4 1.1 1.1 1.1

103 General administrators; national government (HEO to Senior Principal)2 2 2 2 2

110 Production, works and maintenance managers 4 4 1.1 2 1.1

111 Managers in building and contracting 4 4 2 2 2

112 Clerks of works 4 4 2 2 2

113 Managers in mining and energy industries 4 4 1.1 1.1 1.1

120 Treasurers and company financial managers 1.2 1.2 1.1 1.1 1.1

Technical issues

• No one-to-one mapping of CO80 to SOC90• There is a bridge coding which applies to both

1981 and 1991• But 1981 Census occupations not classified

by it!

46%

CO80 SOC90

16%

38%

Comparability of OPCS CO80 occupation codes and SOC90 unit groups

Source: OPCS (1991) “Standard Occupational Classification”, Volume 3, HMSO

Solutions

• Map those occupations which have exact or near-exact linkage

• Add other occupations which are not uniquely linked but map to the same standard NS-SEC analytic groups

• Use empirically based rules to estimate the rest (approx 3% of population)

Part of NS-SEC80 derivation matrix

NS-SEC analytic classes

1981 occupation (CO80) SOC90 Self Self manager super- employeecoding employed employed visor

with withoutemps emps

Judges, barristers, advocates, solicitors 240/241/242 1.2 1.2 1.2 1.2 1.2Chartered and certified accountants 250 1.2 1.2 1.2 1.2 1.2Cost and works accountants 251 1.2 1.2 1.2 1.2 1.2Estimators 360 2 2 2 2 2Valuers, claims assessors 360/1 2 2 1.2 2 2Financial managers 120 1.2 1.2 1.1 1.1 1.1Underwriters, brokers, investment analysts 361 2 2 1.2 2 2Taxation experts 362 1.2 1.2 1.2 1.2 1.2Personnel and industrial relations officers 124/363 2 2 1.1 2 2O and M, work study and OR officers 125/364 1.2 1.2 1.1 1.2 1.2Economists, statisticians, actuaries 252 1.2 1.2 1.2 1.2 1.2Systems analysts, computer programmers 126/214/320 1.2 1.2 1.1 1.2 1.2

Validation – cross-tab of 1993 deaths

nssec_90nssec80 1.1 1.2 2 3 4 5 6 7

1.1 4,823 20 50 0 0 0 0 0 4,8931.2 4 6143 38 33 0 0 0 0 6,218

2 216 89 24,049 828 6 40 33 0 25,2613 0 11 40 20,771 0 0 50 36 20,9084 0 18 0 0 15,026 0 0 0 15,0445 0 0 0 0 0 22,701 113 242 23,0566 0 0 0 191 0 76 33,056 636 33,9597 0 0 0 0 0 16 187 46,615 46,818

Total 5,043 6281 24,178 21,823 15,032 22,833 33,439 47,530 176,157

off diag 220 138 129 1052 6 132 383 914 2974

1.69%

Conceptual problem

• NS-SEC was designed for the economic structure of 2000 not 1980

• May be criticised as conceptually invalid• But empirically, it works!

Period life expectancy – males at birth

Source ONS Longitudinal Study

64

66

68

70

72

74

76

78

80

82

1982-86 1987-91 1992-96 1997-2001 2002-06

Higher managerial &prof

Lower managerial &prof

Intermediate

Small employers

Lower supervisory &tech

Semi-routine

Routine

Period life expectancy – females at birth

Source ONS Longitudinal Study

72

74

76

78

80

82

84

86

1982-86 1987-91 1992-96 1997-2001 2002-06

Higher managerial& prof

Lower managerial& profIntermediate

Small employers

Lower supervisory& tech

Semi-routine

Routine

Period life expectancy – men aged 65

Source ONS Longitudinal Study

10

11

12

13

14

15

16

17

18

19

20

1982-86 1987-91 1992-96 1997-2001 2002-06

Higher managerial& prof

Lower managerial& prof

Intermediate

Small employers

Lower supervisory& tech

Semi-routine

Routine

Period life expectancy – women aged 65

Source ONS Longitudinal Study

10

12

14

16

18

20

22

24

1982-86 1987-91 1992-96 1997-2001 2002-06

Higher managerial &prof

Lower managerial &prof

Intermediate

Small employers

Lower supervisory &tech

Semi-routine

Routine

Summary

• ONS has a series of trends in life expectancy by (RG) social class

• Has now developed a series by NS-SEC also using the ONS Longitudinal Study (published Feb 2011*)

• Similar pattern of socio-economic gradient apparent in results

*For full description of methods and context of results see Health Statistics Quarterly volume

49

http://www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/trends-in-life-expectancy-by-the-national-statistics-socio-economic-classification-1982-2006/health-inequalities-in-the-21st-century.pdf