1. linking lives through time www.lscs.ac.uk THE VALUE OF LONGITUDINAL RESEARCH IN POPULATION GEOGRAPHY Paul Boyle (Tom Cooke, Zhiqiang Feng, Vernon Gayle, Elspeth Graham, Hill Kulu, Paul Norman, Clive Sabel) linking lives through time www.lscs.ac.uk

2. n As more engage with the cultural turn there is a risk that Geography becomes detached from important social issues and concerns n While Population Geography is regarded as a quantitatively strong sub-discipline in Geography, it is weak compared to other disciplines – we face a critical time ahead n Longitudinal data – Population Geographers need to make better use of existing resources n Longitudinal methods – exciting possibilities for a quantitative Population Geography of the future

3. linking lives through time www.lscs.ac.uk Theoretically advanced research Theoretically weak research

4. linking lives through time www.lscs.ac.uk Theoretically advanced research Theoretically weak research Weak research methods Advanced research methods

5. linking lives through time www.lscs.ac.uk Theoretically advanced research Theoretically weak research Weak research methods Advanced research methods Population Geography?

6. linking lives through time www.lscs.ac.uk Quantitative research in Geography

7. linking lives through time www.lscs.ac.uk n It has been argued that an unhealthy divide has developed within the discipline of Geography n Geography is gradually ignoring important social questions for which quantitative analysis is particularly pertinent n The focus on qualitative methods may have gone too far?

8. linking lives through time www.lscs.ac.uk “the rise of a post-modern human geography, with its stress on textuality and texts, deconstruction, critique, reading and interpretation, has led human geography into a theoretical playground where its practitioners stimulate or entertain themselves and a handful of readers, but have in the process become increasingly detached from contemporary social issues and concerns.” Hamnett (2003: 1)

9. linking lives through time www.lscs.ac.uk “there has been a radical shift in the dominant methodology of much human geographical research. Quantitative techniques and aggregate social research have been largely abandoned, in favour of small scale, interpretative, qualitative, in-depth methodologies. Analysis of large data sets has become totally passe, the object of suspicion or even derision as empiricist. Arguably, methodological development has been characterised by a shift from much mindless quantification and measurement to an unquestioning use of qualitative techniques.” (Hamnett 2003: 2)

10. linking lives through time www.lscs.ac.uk “The risk is that much of human geography will cease to be taken seriously in the world beyond the narrow confines of academe. It will be seen simply as a corner of the postmodern theoretical playground, possibly entertaining to study for a while, but something which can be safely ignored while the grown ups get on with the business of changing the world, often for the worse.” Hamnett (2003: 1)

11. linking lives through time www.lscs.ac.uk n Of course, the extent of this problem is debated n Some suggest that quantitative research remains strong in Geography, especially in Population Geography

12. linking lives through time www.lscs.ac.uk “we strongly take issue with his view that quantitative techniques and aggregate social research have been largely abandoned and that geographers no longer analyse large data sets. Indeed such work remains a buoyant component of the contemporary discipline, characterised by much sophisticated analysis of data sets large and small––certainly not mindless quantification and measurement but rather an ordered interrogation.” Johnston et al. (2003: 157)

13. linking lives through time www.lscs.ac.uk n However, while some geographers may continue to use quantitative analysis, few are engaging with longitudinal data n Geographers are failing to take advantage of these ‘jewels in the crown’ n Even fewer are adopting sophisticated longitudinal modelling approaches

14. linking lives through time www.lscs.ac.uk n October 2003 –September 2004, 839 cohort data sets downloaded from the archive (346 users) Datasets downloaded

15. linking lives through time www.lscs.ac.uk Disciplines of individuals downloading datasets

16. linking lives through time www.lscs.ac.uk n There are few quantitatively trained young Population Geography researchers n Despite ESRC’s strong emphasis on the training of quantitative researchers Various training for early- or mid-career researchers PhD students get extra £3000 for quantitative techniques Aiming to influence training in undergraduate degrees

17. linking lives through time www.lscs.ac.uk The value of longitudinal methods

18. linking lives through time www.lscs.ac.uk n Cross-sectional data Single point in time Pooling cross-sectional surveys to examine change through time (e.g. GHS) Measures aggregate, not individual, change

19. linking lives through time www.lscs.ac.uk n Longitudinal data Multiple points in time Panel study with repeated measurements (e.g. BHPS) Cohort studies chart the development of groups from a particular time point (e.g. birth cohorts)

20. linking lives through time www.lscs.ac.uk n The value of longitudinal data analysis Permits insights into the processes of change (mobilities and transitions) Age, period and cohort effects Direction of causality State dependence Residual heterogeneity

21. linking lives through time www.lscs.ac.uk Age 161718192021(Cohort 1) Age16171819(Cohort 2) Age1617(Cohort 3) Age Period Cohort Age, period, cohort effects

22. linking lives through time www.lscs.ac.uk n Cross-sectional data show that the unemployed have poorer health than the employed, but what is the direction of effect? UnemploymentPoor health Direction of causality

23. linking lives through time www.lscs.ac.uk “As far as I'm concerned I'm in good shape. I still love my football. I'm not retiring and my leaving is in no way health related.” (Houllier, May 2004)

24. linking lives through time www.lscs.ac.uk Person APerson B MonthHealth statusEmployment status Health statusEmployment status 117Employed 21 31 41Unemployed 51 61 71 81 91 101Unemployed 111Unemployed 121Unemployed

25. linking lives through time www.lscs.ac.uk Person APerson B MonthHealth statusEmployment status Health statusEmployment status 117Employed17Employed 21 17Employed 31 17Employed 41Unemployed17Unemployed 51 17Unemployed 61 10Unemployed 71 16Unemployed 81 5 91 4 101Unemployed3 111Unemployed2 121Unemployed1

26. linking lives through time www.lscs.ac.uk Person APerson B MonthHealth statusEmployment status Health statusEmployment status 117Employed17Employed 21 17Employed 31 17Employed 41Unemployed17Unemployed 51 17Unemployed 61 10Unemployed 71 16Unemployed 81 5 91 4 101Unemployed3 111Unemployed2 121Unemployed1 Person A unemployed for 9 months, health score 1 Person B unemployed for 9 months, health score 1

27. linking lives through time www.lscs.ac.uk Person APerson B MonthHealth statusEmployment status Health statusEmployment status 117Employed17Employed 21 17Employed 31 17Employed 41Unemployed17Unemployed 51 17Unemployed 61 10Unemployed 71 16Unemployed 81 5 91 4 101Unemployed3 111Unemployed2 121Unemployed1 Person A unemployed for 9 months, health score 1 Person B unemployed for 9 months, health score 1

28. linking lives through time www.lscs.ac.uk State dependence Past behaviourCurrent behaviour

29. linking lives through time www.lscs.ac.uk State dependence Unemployed, t-1Unemployed, t ?

30. linking lives through time www.lscs.ac.uk State dependence Unemployed, t-1 Employed, t-1 Unemployed, t ? ?

31. linking lives through time www.lscs.ac.uk Residual heterogeneity n The possibility of substantial variation between similar individuals due to unmeasured or unmeasurable variables Data collection instruments fail to capture the full complexity of social life No way of accounting for omitted explanatory variables in cross-sectional analysis Techniques exist for accounting for omitted explanatory variables if we have data for an individual at more than one time point

32. linking lives through time www.lscs.ac.uk Making better use of the data we already have

33. linking lives through time www.lscs.ac.uk n The UK has a wealth of longitudinal data n Considerable value in routinely collected administrative data n An under-utilised resource, which has been yet to be properly and consistently harnessed n Relatively cheap and, often, comprehensive in coverage

34. linking lives through time www.lscs.ac.uk n For many reasons, the public are rightly apprehensive about the general erosion of privacy of information Surveillance society… Identity cards… Identity theft… Use of DNA material… Links to insurance cover…

35. linking lives through time www.lscs.ac.uk protection of people’s privacy … versus … creation of bona fide and valuable knowledge about population and society

36. linking lives through time www.lscs.ac.uk Lawrence Gostin 2000 Public Health Law (University of California Press) “Despite my background as a civil libertarian... I question the primacy of individual freedom (and its associated concepts – autonomy, privacy, and liberty) as the prevailing social norm. Freedom is a powerful and important idea, but I think scholars have given insufficient attention to equally strong values that are captured by the notions of partnership, citizenship, and community....”

37. linking lives through time www.lscs.ac.uk 26 th June 2006

38. linking lives through time www.lscs.ac.uk 19 th June 2007

39. linking lives through time www.lscs.ac.uk n We should adopt a culture of data sharing (ESRC are leading the way) n Carefully controlled settings can provide access to data in imaginative ways n Linking data is not risky if careful procedures for data access are in place Safe settings Remote access Special license

40. linking lives through time www.lscs.ac.uk The Scottish Longitudinal Study

41. linking lives through time www.lscs.ac.uk n Modelled on England and Wales LS n Provides linked data from the Scottish Census and administrative records n Sampling based on 20 ‘semi-random’ birthdays (5.5% of the Scottish population) n Initial sample drawn from the 1991 Census (around 274,000 members) n Similar sample drawn from 2001 Census n Link vital events information in the intervening period

42. linking lives through time www.lscs.ac.uk

43. Data sources n Vital statistics Births (SLS birthdate) Births (to sample members) Stillbirths Infant mortality Deaths Widow(er)hoods Divorces n Health data Cancer registrations n Census 1991 Census, 2001 Census Including data on occupation, economic activity, social class, housing, ethnicity, age, sex, marital status, household composition, health, education, country of birth, migration, workplace, religion etc. Information on SLS member and other household members n Population data Immigration Emigration

44. linking lives through time www.lscs.ac.uk Data sources n Vital statistics Births (SLS birthdate) Births (to sample members) Stillbirths Infant mortality Deaths Widow(er)hoods Divorces Marriages n Health data Cancer registrations Hospital episodes n Census 1991 Census, 2001 Census Including data on occupation, economic activity, social class, housing, ethnicity, age, sex, marital status, household composition, health, education, country of birth, migration, workplace, religion etc. Information on SLS member and other household members n Population data Immigration Emigration

45. linking lives through time www.lscs.ac.uk

47. The future…? n Linkage of additional data… Educational data (school census and exam results) Small-area geographical estimates of income and health-related behaviours And the exciting opportunity to link back through time

48. linking lives through time www.lscs.ac.uk

55. n The SLS and datasets like it have great potential for population geographers n The large sample allows better geographical resolution n The integration of census and vital events information is particularly relevant to topics in Population Geography

56. linking lives through time www.lscs.ac.uk Research 1: MND in Finland

57. linking lives through time www.lscs.ac.uk Motor Neurone Disease in Finland, 1985-1995

58. linking lives through time www.lscs.ac.uk Genetic or environmental influences?

59. linking lives through time www.lscs.ac.uk

62. Died Middle Born

63. linking lives through time www.lscs.ac.uk CasesControls Stayed Moved away 102 122 82 137

64. linking lives through time www.lscs.ac.uk Research 2: Suburban fertility

65. linking lives through time www.lscs.ac.uk

67. n Distinct clusters of low and high fertility, in urban centres and suburban surrounds n Why is fertility higher in suburban areas? n Suburban compositional, contextual or selective migration effects? n Explore Finnish fertility histories…

68. linking lives through time www.lscs.ac.uk

69. Research 3: Migration and health

70. linking lives through time www.lscs.ac.uk Health MigrationDeprivation

71. linking lives through time www.lscs.ac.uk Health MigrationDeprivation There is a deprivation gradient for health status Healthy people live in less deprived locations and vice versa

72. linking lives through time www.lscs.ac.uk Healthy are more likely to migrate than unhealthy Unhealthy elderly are more likely to migrate than healthy Health MigrationDeprivation There is a deprivation gradient for health status Healthy people live in less deprived locations and vice versa

73. linking lives through time www.lscs.ac.uk Healthy are more likely to migrate than unhealthy Unhealthy elderly are more likely to migrate than healthy More advantaged people tend to migrate towards less deprived locations? Less advantaged people tend to drift into (or be trapped in) the more deprived locations? Health MigrationDeprivation There is a deprivation gradient for health status Healthy people live in less deprived locations and vice versa

74. linking lives through time www.lscs.ac.uk Age standardised rates of limiting long-term illness: total population

75. linking lives through time www.lscs.ac.uk Age standardised rates of limiting long-term illness: all migrants

76. linking lives through time www.lscs.ac.uk Age standardised rates of limiting long-term illness: long-distance migrants

77. linking lives through time www.lscs.ac.uk Limiting long-term illness

78. linking lives through time www.lscs.ac.uk

81. Conclusion

82. linking lives through time www.lscs.ac.uk n A criticism of Population Geography is that it has not been swept up in the cultural turn as much as other sub-disciplines within Geography n For some, this may be a strength n Yet, while Population Geography has retained a quantitative tradition, these skills are gradually disappearing

83. linking lives through time www.lscs.ac.uk n The quantitative skills among Population Geographers are weak compared to other disciplines n We face a critical time ahead n Longitudinal data and methods provide possibilities that Population Geographers should take more advantage of