Influence of Households on Drinking Behaviour: a Multi-level analysis

1. Influence of Households on Drinking Behaviour: a Multi-level analysis Roy Carr-Hill (and Nigel Rice) Centre for Health Economics University of York

2. Background • Long term heavy drinking associated with increased risk of wide range of conditions • Drinking guidelines established to enable individuals to monitor alcohol consumption • Most research is on role of atomised (rational) consumer • Purpose of paper to explore influence of group, especially household, membership

3. Area or Household Effects • Edwards et.al.(1994) social interaction theory • Four possible mechanisms: • Physical environment • Cultural milieu • Place deprivation • Selective mobility • Growing literature on importance of place, although often without sufficient controls • More fundamental groupings more likely

4. Data and methods • 1993 Health Survey for England 17,687 interviews aged 16+ living in 9,700 hhds Size N hhds % 1 3393 39 2 4299 49 3 787 9 4 218 2 5+ 40 (-)

5. Independent Variables • Personal: age, sex (NOT gender) • Social environment: persons in hhd, single or partnered, perceived social support • Health: perceived stress • Health related behaviour: physical activity • Education: formal qualifications • Socio-economic: car ownership, social class, economic activity, income support • Problem -other health variables - likely to be jointly determined with drinking

6. Dependent Variable • N units of alcohol drunk in previous week • Empirical distributions highly skewed • Constant of unity added to all observations before taking natural logs • Other analysis (e.g. Sutton and Godfrey, 1995) relied on dummy variables to reflect other hhd members drinking • Assumed this is externality

7. Multi-Level framework • Model area and household effects as random components • Allow for clustering (intra-class correlation) within both hhds and eventually areas • Three models specified • Basic model with age and sex • Individual model with individual variables • Full model with both hhd and indiv vars

9. Fixed Effects • Males • Difference decreased with age • Single people consume more • Physically active consume more • Lack of social support had no effect • Economically inactive consume less but mitigated by hhd size and car ownership • Clear social class gradient • Those on income support consume less but effect disappear with hhd vars

10. Household characteristics and Random Level Effects • Household size important • Car ownership (reflecting permanent income) • Multiple car ownership • Most variance between individuals (56%) with 42% at hhd level and 2% area level • Once again geographical contextual vars are an academic hypothesis > a reality • With full model, proportions change to 55% individual, 39% hhds and 2% area

11. Conclusions: I • Large proportion of unexplained variation in individual alcohol consumption can be attributed to household membership • Nearly as large as contribution of unexplained differences between indivs • Policies should address households as well as individuals and support analysis of impact of taxes on consumption levels

12. Conclusion: II • Intra-household effects are often important and can be addressed with many surveys • Especially important for attitudinal and behavioural variables • Place effects are often exaggerated