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 SizeN hhds % 13393 39 2429949 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

8. % very Low % High or very high Average units /week Females16-342877.7 35-543257.1 55-744934.5 75+5923.0 males16-34151719.7 35-54151718.7 55-74241214.8 75+4048.9

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